How to repair the boot sector (MBR) and how to use Testdisk in Windows 10 and 11

This time, we will explain how to repair the boot sector (MBR) in Windows 10 and Windows 11.

The boot sector is the first sector of a hard disk, and if it becomes corrupted, Windows will not start properly.

In this article, we will explain the cause of this boot sector problem and how to use Testdisk to repair it, so we hope you will find it useful.

Causes and error messages of boot sector (MBR) corruption

This article explains the causes of boot sector (MBR) corruption and the error messages that appear when the boot sector is corrupted.

• Causes of boot sector (MBR) corruption
• What error message will appear if the boot sector (MBR) is damaged?

Causes of boot sector (MBR) corruption

The causes of boot sector (MBR) corruption include:

• Forced termination or shutdown at inappropriate times due to power outages, etc.
• Bad sectors on hard disk
• Impact of the virus
• Deletion of startup files due to incorrect operation etc.
• Disk error or failure
• Overwriting MBR by OS installation

What error message will appear if the boot sector (MBR) is damaged?

If the boot sector (MBR) becomes corrupted, you may receive an error message similar to the one below.

• Bootmgr is missing

The message is that a file required to start Windows cannot be found.
This error occurs due to MBR corruption, etc.

• Error loading operating system

This error may appear when an inconsistency occurs, such as when the hard disk configuration information is damaged.

• Operating System not found

The message is that the OS cannot be found. In addition to incorrect device loading order, other possible causes include MBR errors, corrupted system files, and corrupted BIOS.

• Reboot and Select proper Boot device or Insert Boot Media in selected Boot device and press a key

The BIOS cannot find the boot disk due to a defective SATA slot or hard disk failure.

It is also possible that the BIOS boot order is incorrect.

Also, MBR corruption is suspected.

How to repair boot sector (MBR) using free software

If a problem occurs with the boot sector (MBR), there is a way to repair it using free software.

This article explains the main free software that can repair the boot sector and how to use it.

• Representative free software that can repair boot sector (MBR)
• How to repair boot sector (MBR) using TestDisk
• How to Repair Boot Sector (MBR) with MiniTool Partition Wizard Free
• How to repair boot sector (MBR) using AOMEI Paritition Assistant

Representative free software that can repair boot sector (MBR)

Free software that can repair the boot sector (MBR) includes the following:

When attempting to repair the MBR using these software, it is recommended to back up as much data as possible on the hard disk.

• TestDisk
• MiniTool Partition Wizard Free
• AOMEI Parity Assistant

How to repair boot sector (MBR) using TestDisk

"TestDisk" is free software that can modify and restore partition-related information.

Here's how to repair the boot sector (MBR) using TestDisk.

[How to repair the boot sector (MBR) using TestDisk]

1. TestDisk Download – CGSecurityGet the software at
2. Start TestDisk
3. Select "Create"
4. Press "Enter" key
5. Select the disk you want to restore and select "Proceed"
6. Select partition type
7. Select “MBR Code”
8. Press "Y" key
9. A confirmation screen will appear, so if there is no problem, press the “Y” key.
10. Restart your computer when finished

How to Repair Boot Sector (MBR) with MiniTool Partition Wizard Free

"MiniTool Partition Wizard Free" is a software for MBR repair.

Here's how to repair boot sector (MBR) using MiniTool Partition Wizard Free:

[How to repair boot sector (MBR) using MiniTool Partition Wizard Free]

1. Free Partition Management Software – MiniTool Partition Wizard Free EditionInstall it on a PC that is not experiencing the problem.
2. Launch MiniTool Partition Wizard Free
3. Select "Bootable Media"
4. Connect the created bootable media to the PC with the problem
5. Change the BIOS boot order so that bootable media has priority
6. Boot your PC from bootable media
7. Recovery environment starts
8. Select the appropriate system disk
9. Select "MBR Rebuild"
10. Select "Apply"
11. Once completed, restart your PC and check

How to repair boot sector (MBR) using AOMEI Paritition Assistant

"AOMEI Paritition Assistant" is a partition management tool.

Here's how to repair boot sector (MBR) using AOMEI Paritition Assistant:

[How to repair boot sector (MBR) using AOMEI Paritition Assistant]

1. AOMEI Download CenterGet the AOMEI Paritition Assistant software at
2. Right click on the MBR disk you want to repair
3. Select "Rebuild MBR"
4. Select Windows OS version
5. Select "Apply"

How to repair boot sector (MBR) using command prompt

If a problem occurs with the boot sector (MBR), there is also a way to repair it using the command prompt.

If Windows does not start, you will need an installation media to start the command prompt, so we recommend creating it using the method below.

[How to create installation media]

1. Downloading a Windows 10 disk image (ISO file)or
   Download Windows 11Download the installation media file at
2. Connect the creation media (USB, DVD, etc.) to the PC
3. I accept the license terms
4. Select "Create installation media for another PC (USB flash drive, DVD, or ISO file)"
5. Select "Next"
6. Select the language, architecture, and edition that best suits your computer.
7. Uncheck "Use recommended options for this PC"
8. Select "Next"
9. Select "ISO file"
10. Select "Next"
11. If you want to write to a DVD, select "Open DVD writing drive"
    1. If you don't have a DVD inserted, put it in the drive and select "Burn".
    2. Select "Close" when finished
12. When writing to USBRufus – Easily create bootable USB drivesuse software such as
    1. After downloading Rufus, start it by double-clicking it.
    2. Select the USB you want to create media on your device
    3. Select the obtained ISO file
    4. Select "Start"
    1. Select "Close" when finished

[How to repair boot sector (MBR) using command prompt]

1. Boot your PC from installation media
2. Select settings
3. Select "Next"
4. Select "Repair your computer"
5. Select “Troubleshooting” from “Choose an option”
6. Select “Command Prompt” in “Advanced Options”
7. Enter "bootrec /FixMbr"
8. Press "Enter" key
9. Enter "bootrec /RebuildBcdr"
10. Press "Enter" key
11. Once completed, restart your PC and check

If you try to repair using the Bootrec command explained here, but it does not work because it is blocked, please try the following method.

How to repair boot sector (MBR) using Diskpart

Here's how to repair boot sector (MBR) using Diskpart:

To be exactHow to repair boot sector (MBR) using command promptThis is a workaround for cases where it does not work due to being blocked, etc.

[How to repair boot sector (MBR) using Diskpart]

1. Boot your PC from installation media
2. Select settings
3. Select "Next"
4. Select "Repair your computer"
5. Select “Troubleshooting” from “Choose an option”
6. Select “Command Prompt” in “Advanced Options”
7. Type "diskpart"
8. Select "Enter" key
9. Check which is the boot disk using "List disk"
10. Enter "select disk n" (where n is the disk number) and press Enter.
11. Type "list volume" and enter
12. Type "select volume m" (where m is the EFI partition volume number) and press Enter.
13. Enter "assign letter=N: (drive letter you want to assign)" and press Enter.
14. Type "Exit" and enter
15. Enter "N: (N is the assigned drive letter)" and press Enter.
16. Enter "format N: /FS:FAT32" and enter
17. Type "bcdboot C:\windows /s N: /f UEFI" and Enter
18. againHow to repair boot sector (MBR) using command prompttry running

How to repair the boot sector (MBR) of an SSD or external HDD (USB drive)

This article explains how to repair error messages such as "Operating System Not Found", "Missing Operating System", and "Invalid Partition Table" when connecting an SSD or external HDD. Masu.

If an error such as "Operating System Not Found", "Missing Operating System", or "Invalid Partition Tab" is displayed when you start up your computer after connecting an external HDD, the external HDD may not be the drive where Windows is installed. may have been started with priority.

If there is no problem after removing the external HDD and booting, the cause of the error may be the boot priority.

Try booting the BIOS and changing it so that the drive where the Windows OS is installed is booted first.

Also, if the error is not like the one above, try the solution mentioned above.

How to repair the boot sector (MBR) of a USB memory

There are cases where rebuilding the MBR is effective even if the USB cannot be opened.

However, please be careful as the following steps may result in data loss.

The method to repair the boot sector (MBR) of a USB memory is as follows.

[How to repair the boot sector (MBR) of a USB memory]

1. Free Partition Management Software – MiniTool Partition Wizard Free Editioninstall
2. Launch MiniTool Partition Wizard Free
3. Select "Disk & Partition Management"
4. Right click on the USB memory
5. Select "MBR Rebuild"
6. Right click on the partition
7. Select "Format"
8. Select "Apply"
9. Select "Pending Operations"

Even if it doesn't work the first time, you may be able to open it by repeating the same steps.

Summary of how to repair boot sector (MBR) in Windows 10 and 11

This time, we explained how to repair the boot sector (MBR) in Windows 10 and Windows 11.

Boot sector corruption and malfunctions can occur for a variety of reasons, including improper shutdown or the effects of viruses.

If the MBR is malfunctioning, Windows may not be able to start properly, and therefore installation media may be required to repair it.

If you create an installation media in case this happens, you will be able to perform the repair smoothly.

There are some free software that can repair MBR, so try using them first to see if you can repair it.