Bad Boot Sector Corrupt MBR: 4 Easy Ways to Repair it

A corrupted MBR or boot sector means a lot of trouble. You’ll have difficulty booting into Windows until you deal with it.

If you’ve tried to boot into Windows 10 and the boot sector error appeared on a dark screen, this almost always points toward corrupt MBR or critical HDD failure.

We have a few ways to resolve this, so check the steps below.

What causes MBR corruption?

From user experience, we gather that MBR (Master Boot Record) corruption can be caused by various factors, including any of the following:

• Malware or virus infections – Malicious software can damage or corrupt the MBR, making the system unbootable.
• Hardware issues – Problems with the hard disk, such as bad sectors or disk failure, can cause the corruption of the MBR.
• Power surges – Power surges or sudden power failures can interrupt the boot process and cause corruption of the MBR.
• Human error – Deleting or modifying the MBR can cause it to become corrupted and prevent the system from booting.
• Operating system errors – Errors during the installation or configuration of the operating system can also lead to MBR corruption.

Do note that the solutions we will recommend below will resolve the following related MBR issues:

• MBR keeps getting corrupted – MBR is essential every time you start your computer. That’s why tune-up utilities such as Ashampoo Win Optimizer are mandatory for dealing with HDD issues.
• Is MBR corrupted? Can’t use mouse/keyboard – If your PC fails to recognize them, don’t hesitate to apply the solutions detailed in this guide on how to fix mouse or keyboard not detected.
• Power outage MBR corrupt – An improper shutdown or power glitch can easily corrupt the MBR. If the issue persists, use this guide dedicated to fixing power outage consequences.
• Can’t boot MBR corrupt – bootrec – A confirmed solution for the issue is to use a command prompt and run the bootrec. Rebuilding MBR is described in detail above.

What can I do if a boot sector is corrupted?

1. Use third-party optimization tools
2. Scan for HDD errors
3. Rebuild MBPR
4. Perform a clean reinstallation

1. Use third-party optimization tools

This isn’t one of those common errors you’ll deal with regularly. Instead, issues with the boot sector mainly occur due to HDD corruption or misuse of specific system files.

The black screen and boot failure are pretty intimidating for an inexperienced user. However, using Ashampoo Win Optimizer can resolve them with no extra effort.

This incredible optimization is known for its great HDD scans, brand-new Defrag with minimal performance drain to worry about, and accurate analysis logs.

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Ashampoo Win Optimizer is the go-to tune-up utility when facing large-scale MBR issues.

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2. Scan for HDD errors

1. Boot with the USB installation media and press the Shift + F10 keyboard shortcut to open the Command Prompt.
2. In the command line, type the following script and hit Enter. 
   chkdsk /f /r
   
3. After resolving the HDD issues, restart your PC and try booting into Windows again.

A boot sector failure and MBR corruption won’t occur without any reason. This mostly happens in scenarios when your HDD is on its deathbed, and you should seriously consider replacing it.

This is, on many occasions, a clear sign that you should back up your data as soon as possible, as the HDD either has corrupted sectors or it’s malfunctioning.

On the other hand, this isn’t a rule of thumb. So before you ditch your storage, make sure to inspect it. Some errors can be repaired with the proper tools, either third-party tools or a built-in ChkDsk.

You can run chkdsk from the command line in a System Repair section if you cannot boot. This is a relatively simple task, but it still requires bootable media.

3. Rebuild MBR

1. Insert the Windows 10 bootable media (USB stick or DVD) and restart your PC.
2. During restart, enter your BIOS; you may do this by pressing F10, F2, F12, or F1 during restart.
3. Navigate to the Boot menu, and set the bootable media as the primary boot device with the Windows 10 installation. Then, change the boot order by entering the Boot menu or within BIOS settings.
   
4. Press any key to boot.
5. The loading process of the installation file should commence.
6. Select the preferred language, time/format, and keyboard input. Hit the Next button.
   
7. Select Repair your computer from the bottom left corner in the following dialog box.
   
8. Open Troubleshoot from the selection menu.
   
9. Choose Advanced Options.
   
10. Open Command Prompt. If prompted, select your account and enter the password.
    
11. In the command line, type the following commands and press Enter after each:
    • bootrec /FixMbr
    • bootrec /FixBoot
    • bootrec /ScanOs
    • bootrec /RebuildBcd
12. Exit, remove the installation drive, and try starting the system in the usual manner.

Rebuilding the MBR and fixing the boot sector error is one way to solve this problem. However, this requires specific preparations made on another PC.

You must download the Media Creation Tool and create a bootable installation drive. You can use a DVD and burn the setup files, but we prefer a USB flash drive with at least 6 GB of storage space.

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4. Perform a clean reinstallation

1. Download the Media Creation Tool.
2. Plug in the USB flash drive with at least 6 GB.
3. Run Media Creation Tool and accept the License Terms.
4. Choose Create installation media (USB flash drive, DVD, or ISO file) for another PC, then hit Next.
   
5. Choose the fitting language, architecture, and edition, and click Next.
   
6. Select USB flash drive and then click Next.
7. Media Creation Tool will download the setup and copy the installation files onto the USB flash drive.
8. Plug the USB drive into a troubled PC and boot from it.
9. Enter all required information and choose Install Windows only.
10. Format the system partition and install Windows 10 there.

In the end, if you’re confident that your HDD is in good health but still unable to boot into Windows, we can only suggest a clean reinstallation.

This, of course, means you’ll lose all data from the system partition. So, if there’s any way for you to connect your HDD to another PC and back up the data – do it.

After that, we can boot with the installation media and install a clean version of Windows. That way, the problem should be resolved.

With that said, we can conclude this article. In case you have additional questions or possibly an alternative way to fix corrupt MBR, feel free to tell us in the comments section below.