Accidentally deleted system reserved partition or accidentally deleted EFI boot partition Windows 10? Windows can't boot after deleting system partition? Don't worry! Now, this post will show you 3 ways to recover deleted system partition or fix unbootable Windows. Try them and then you can use the PC properly.

Windows Can’t Boot after Deleting System Partition

You would feel helpless and desperate when Windows can’t boot if you mistakenly deleted system reserved partition or EFI boot partition.

Tip: Since there are 2 types of booting mode, namely Legacy BIOS + MBR and UEFI + GPT, we talk about this issue from 2 aspects.

What Is System Reserved Partition ( Legacy BIOS + MBR)

When installing Windows 7/8/10 on a clean disk which is initialized to MBR, the setup will create a system reserved partition at the beginning of the hard disk and mark it active.

This partition holds the Boot Configuration Database (BCD), Boot Manager (BOOTMGR), Windows Recovery Environment and reserves space for the startup files which may be required by BitLocker, among which BCD and BOOTMGR are vital parts to start Windows. 

If the active system reserved partition is lost, Windows will be unbootable since no BOOTMGR and BCD are found. And you may receive error messages like BOOTMGR is missing or Operating System not found.

What Is EFI System Partition (UEFI + GPT)

When you install Windows on a clean disk that is initialized to GPT, Setup will create an EFI partition (ESP). It contains the boot loaders or kernel images for all installed operating systems. 

When a computer is powered on and booted, UEFI firmware loads files stored on the EFI system partition to start installed operating systems and various utilities.

If you accidentally deleted EFI boot partition in Windows 10, Windows will be naturally unbootable due to missing boot files. 

It Is Possible to Fix Unbootable Windows Due to System Partition Deletion

But luckily, you still have a chance to make the unbootable Windows bootable again, and no reinstallation is required or at least reinstall without losing personal data. That is to recover deleted system partition or fix boot information. 

Tip: Deleting a partition in Windows just clears or modifies corresponding partition information in the partition table, making Windows unable to locate the partition, and the actual partition still reside in its place until the new partition is created there. Therefore, as long as you rebuild partition table, the lost partition would be visible for both Windows and users.

Then, let’s see how to do the recovery. 

3 Tested Ways to Fix Windows Can’t Boot after Deleting System Partition

Here, we mainly introduce 3 ways to restore deleted system partition: use a free third-party program, employ diskpart of Windows installation disc, and reinstall Windows without losing personal files. 

Tip: Please try the first method, then the second one, and the last one. Try the latter only when the former failed to work.

Method 1: Fast Recover Deleted System Partition with MiniTool Partition Wizard Bootable Edition

This is the simplest method, and it perfectly worked on our testing machine. 

MiniTool Partition Wizard Bootable Edition can help Windows users complete various partitioning operations when Windows is unbootable, including recover lost/deleted partition, rebuild MBR, resize system partition/boot partition, clone disk/partition, and so on. 

To use this bootable partition manager to recover partition, you should purchase a paid version. If you are not a Server user, the Professional Ultimate Edition is available. 

After you register the software, you can use the Bootable Media to build the boot CD/DVD discs and boot flash drive. See the guide here: How to Build Boot CD/DVD Discs and Boot Flash Drive with Bootable Media Builder

Tip: As mentioned above, Windows can’t boot after deleting system partition issue includes two situations: missing/no system reserved partition or accidentally deleted EFI partition Windows 10. Here, MiniTool Partition Wizard can help recover deleted system reserved partition and EFI partition.

Here, take how to restore system reserved partition Windows 10 as an example.

Step 1: Choose a Feature to Restore Deleted System Partition

  1. Run your computer from this disc that is created before. 
  2. After a successful startup, enter the main interface of MiniTool Partition Wizard. 
  3. Right-click on the disk where system partition was originally located and choose Partition Recovery from the context menu.

choose partition recovery of MiniTool Partition Wizard

Step 2: Choose a Scanning Range

  1. Set scanning range for the selected disk from 3 ranges.
  2. Click Next.

scanning range settings

Step 3: Set Scanning Method for the Selected Scanning Range

  1. You can try choosing Quick Scan at first because it requires much less time. If this method fails to find the needed partition(s), go back to this interface again and choose Full Scan.
  2. Later, click Next.

scanning method settings quick or full scan

Step 4: Choose Searched Partitions

  1. Once partitions MiniTool Partition Wizard detects are listed, please check all useful partitions, both existing and lost/deleted, because unchecked partitions will be lost. 
  2. Click the Finish button.

check all partitions to restore

Step 5: Set Partition Active and Apply all Changes

  1. After finishing the partition recovery, there is one thing you should do. And that is to select the recovered system reserved partition and set it active.
  2. At last, click the Apply button to make all changes finally performed.

click apply to make all changes effective

Tip: Here, we only show you how to restore system reserved partition Windows 10. If you accidentally deleted boot partition (EFI), the steps are the same and read this post How to Restore Deleted Windows Partition after Windows Can’t Boot to learn more information.

“Windows can’t boot after deleting system partition? MiniTool Partition Wizard Bootable Edition can recover deleted system partition with several simple steps in Windows 10.”Click to Tweet

After recovering system partition, you should be able to boot Windows again. Nevertheless, if this method fails to work, you may need to fix boot, which is our second method.

Method 2: Fix Boot Information with Windows Installation Disc

Note: We have tested the following methods on a virtual machine, which are finally proved to be useful to fix unbootable OS when Windows can’t boot after deleting system partition. So, it is worth trying them, but we can’t 100% guarantee that they work for you.

To use this method, please prepare a Windows installation disc which had better be the one you used to install Windows. Of course, the one holding the same version as your Windows is also available. 

Then, you can start fixing. 

However, since there are 2 types of system partitions, namely system reserved partition and EFI system partition, we will show operations separately. 

For Legacy BIOS Users

This method will not create a new system reserved partition but do fix only. So, if you want such a partition, try other methods.

To rebuild system reserved partition in Windows 10, firstly, please boot the computer from the installation media to get the interface below: 

Windows 10 installation media

Then, press on Shift + F10 combination keys to call out Command Prompt, and type following characters. Every type in Command Prompt, as well as Diskpart, should end with pressing on Enter key.

In the window of Command Prompt, type diskpart to activate this partitioning tool. Then, type the following commands to set Windows OS partition (C drive most of the time) active: 

List disk 

Select disk # (# is the number of the disk where your Windows is installed) 

List partition 

Select partition # (Here # is the number of the Windows OS partition rather than system reserved partition) 


rebuild system reserved partition

After setting the partition active, quit from diskpart. 

Then, in Command Prompt please type the following commands to fix boot information to repair system reserved partition in Windows 10: 

Bootrec /fixmbr 

Bootrec /fixboot 

Bootrec /rebuildBCD 

The bootrec /rebuilBCD command will search for Windows installations not included in the Boot Configuration Data (BCD) and then ask you if you’d like to add one or more to it. Just type Yes and then quit from Command Prompt. 

Then, you can take out the installation media, and your Windows is very likely to be bootable again. 

For UEFI Users

Before fixing boot, please launch MiniTool Partition Wizard Bootable Edition to view partition layout at first. In the section Fast Recover Deleted System Partition with Partition Wizard Bootable Edition,

we have introduced how to create a bootable partition manager, so here we skip this step. 

Once the bootable partition manager is created, boot your computer via the disc. Then, MiniTool Partition Wizard will show you disk and partition layout. 

If there is no unallocated space for EFI system partition on the left side of C drive, you can shrink your C drive via the Move/Resize Partition function to create one, which could be the size of your original EFI partition or larger.

If there is such an unallocated space, skip this step, and just select the very unallocated space, create a FAT32 partition here, and label the partition with EFI system

Note: You can’t format the EFI partition to NTFS, because UEFI firmware does not recognize NTFS.

At last, click the Apply button to make all changes executed. 

After that, you can quit from MiniTool Partition Wizard and start your computer via Windows installation media. Then, press on Shift + F10 combination keys to activate Command Prompt and type the following command to repair EFI partition Windows 10: 

bcdboot C:\windows 

Bcdboot copies boot files from the Windows partition to the EFI system partition and creates the BCD store in the same partition. 

Tip: If Windows isn’t installed in C drive, please replace C with the letter of your exact Windows OS partition.

Then, you can remove the Windows installation disc and restart your computer. This way is helpful to repair EFI partition when Windows can’t boot after deleting system partition.

“There are ways to help both Legacy BIOS and UEFI users fix boot information of Windows. Tweet our ways to help more people repair their unbootable Windows.”Click to Tweet

Nevertheless, if you fail to make your Windows bootable again after restoring system served partition and fixing boot information, you’ll need to reinstall Windows.

Method 3: Reinstall Windows Without Losing Any Personal Files

To fix unbootable Windows after you accidentally deleted system reserved partition or boot partition, the last way you can do is to reinstall Windows 10.

Nevertheless, before doing the reinstallation, please transfer your personal files out from C drive, because reinstalling Windows will cause data loss. 

Back up Personal Files from Unbootable Computer

To do this work, we recommend using the professional backup software for Windows 10/8/7 – MiniTool ShadowMaker. With it, you can easily back up your personal files even though the system is unbootable.

MiniTool ShadowMaker TrialClick to Download100%Clean & Safe

Similarly, you need to use Media Builder to create a bootable disc or USB flash drive, boot the PC and enter the MiniTool recovery environment based WinPE. Next, start the file backup.

Step 1: Run MiniTool ShadowMaker.

Step 2: Go to the Backup page, choose files that you need to back up and select the destination path for the backed files.

Step 3: Click Back up Now to immediately run the file backup.

MiniTool ShadowMaker back up files

How to Back up Data without Booting Windows? Easy Ways Are Here!
How to Back up Data without Booting Windows? Easy Ways Are Here!

PC is not booting but you want to back up files without booting to save them? This post will show you how to back up data from a computer that won’t boot.

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Once the backup is completed, you can reinstall Windows without worrying about losing personal files.

How to Reinstall Windows 

Windows reinstallation is not an easy thing. If you are not very clear of steps to install Windows, you can refer to the post How to Reinstall Windows 10 without CD/USB Easily (3 Skills) to get some instructions.

Final Words

Windows can’t boot after deleting system partition? Now, try above methods to recover deleted system partition, repair EFI partition/system reserved partition or reinstall Windows to fix unbootable Windows 10 if it can’t boot after you accidentally deleted system reserved partition or EFI boot partition.

Should you have any questions on this post, just feel free to leave us a message in the Comment part or contact [email protected].

Deleted System Reserved Partition FAQ

What happens if you delete system reserved partition?
System Reserved Partition contains the boot loader files, so Windows cannot boot properly if you delete it.
How do I restore a deleted Windows partition?
  1. Run MiniTool Partition Wizard Bootable Edition.
  2. Right-click the target disk to choose Partition Recovery.
  3. Choose a scanning range.
  4. Select a scan method.
  5. Choose searched partitions.
  6. Set the Windows partition active.
  7. Click Apply.
Can I delete EFI partition Windows 10?
You cannot delete EFI partition in Windows 10. If you delete it, the system will be unbootable because of the lack of boot files.
Can I delete the OEM reserved partition?
It is safe for you to delete the OEM partition that is usually created by computer manufacturers. It usually contains a vendor’s software to perform a one-click factory restore setting.
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