You may never feel strange by those error messages: "Operating System not found" or a blank screen without any message when you boot the computer? Sometimes you may corrupt Windows' MBR (Master Boot Record) unintentionally and come with the problem of failing to enter the system. In this situation, rebuilding MBR rather than reinstalling Windows will be much more convenient and time-saving.

EaseUS has already offered the function to rebuild MBR in the case of boot failure due to MBR problems. Please see the following step-by-step instructions to rebuild MBR. 

Before we start, check the overview of how to rebuild or repair MBR:

⏱️ Duration 3-7 minutes (depending on your method)
💻 Supported Systems Windows 11/10/8/7 and Windows XP
⛑️ Preparations Windows PC, bootable disk
⛏️ Tools EaseUS Partition Master, CMD
👣 Difficulty

🏅3 simple steps with EaseUS Partition Master...Full steps

🥈6 complex steps with CMD...Full steps

How to Rebuild or Repair MBR with EaseUS Partition Master

EaseUS Partition Master is a professional third-party tool for disk and partition. It offers the "Rebuild MBR" feature to help you deal with any problems related to the master boot code problem. It provides a one-stop service to create a WinPE bootable disk and then rebuild MBR. With a simple interface for all people to use.

Free download this powerful tool and try it:

Free Download 

Windows 11/10/8/7100% Secure

Step 1. Create a WinPE bootable disk

  • Launch EaseUS Partition Master, and click "Bootable Media" on the toolbar. Select "Create bootable media".
  • Click "Next" to finish the process.
create a bootable disk

Step 2. Boot EaseUS Partition Master Bootable USB

  • Connect the bootable USB or CD/DVD to your PC. 
  • Press F2 or Del when you restart the computer to enter the BIOS screen. Set and boot your computer from "Removable Devices" or "CD-ROM Drive". And then EaseUS Partition Master will run automatically.

Step 3. Rebuild MBR

  • Click "Toolkit" and choose "Rebuild MBR".

rebuild MBR

  • Select the disk and the type of MBR. Then, click "Rebuild".
rebuild MBR
  • After that, you can see "MBR has been successfully rebuilt on Disk X".
rebuild MBR

This rebuild MBR feature can fix the master boot code problem but can not solve your problem if the Windows Operating System files are corrupted. Besides, creating a WinPE bootable disk is unavailable in EaseUS Partition Master, which can help you access and manage your computer disks/partitions when your OS cannot boot.

See also:

Using CMD to Rebuild MBR

This part will introduce how to use another Windows 10 boot repair tool - CMD to rebuild MBR. For different systems, we provide different guides:

Repair MBR in Windows 10/8/8.1

Fix MBR in Windows 7

Repair MBR in Windows XP

Whatever your system is, you can find solutions in this part. But you need to be careful when putting the commands.

1. Repair MBR in Windows 10/8/8.1

Step 1. Boot from the recovery USB or the original installation DVD.

Step 2. Move to the install screen, and click Repair your computer.

repair your computer

Step 3. On the Choose an option screen, choose Troubleshoot > Advanced Options > Command Prompt

rebuild or fix mbr in windows 10

Step 4. Input the command lines and press Enter each time: 

  • bootrec /fixmbr
  • bootrec /fixboot
  • bootrec /scanos
  • bootrec /rebuildbcd

rebuild or fix mbr in windows 8

Step 5. Remove the DVD/USB from your PC.

Step 6. Input exit and restart your PC.

2. Fix MBR in Windows 7

Step 1. Boot your PC from the installation DVD.

Step 2. You can see "Press any key to boot from CD or DVD", press any key to boot from the DVD.

Step 3. Select a language and select a keyboard layout.

Step 4. Click Next.

Step 5. Choose the operating system and click Next. Check "Use recovery tools that can help fix problems starting Windows".

Step 6. At the System Recovery Options screen, select Command Prompt.

windows mbr fix

Step 7. Type the command lines and hit Enter each time:

  • bootrec /fixmbr
  • bootrec /fixboot
  • bootrec /rebuildbcd

rebuild or fix mbr in windows 7

Step 8. Remove the DVD/USB from your PC, and type exit. Restart your computer.

3. Repair MBR in Windows XP

Step 1. Boot from the Windows XP CD.

Step 2. Press any key to boot from the CD.

Step 3. Then you can see the Welcome to the Setup screen, press R to run Recovery Console.

xp recovery console

Step 4. Answer the question.

"Which Windows installation would you like to log onto" - type 1 and press Enter.

"Type the Administrator password" - input the password and press Enter.

Step 5. Type fixmbr and press Enter.

"Are you sure you want to write a new MBR?" - press Y and hit Enter.

Step 6. Remove the Windows XP CD and type exit.

Step 7. Restart your PC.

After learning the tutorial, let's continue to figure out the definition of MBR and the background of rebuilding MBR. And then, you can be careful of the situation. If you like these methods, click the social buttons to share them with others in need.


What Is MBR

Have you figured out what MBR is? MBR is the abbreviation of Master Boot Record, which is also known as the master boot sector. It is the first sector that must be read when the PC is turned on to access the hard disk. Here is the definition from Wikipedia:

MBR holds the information on how the disc's sectors (aka “blocks”) are divided into partitions. The MBR also contains executable code to function as a loader for the installed operating system—usually by passing control over to the loader's second stage, or in conjunction with each partition's volume boot record (VBR). This MBR code is usually referred to as a boot loader. 

In short, the MBR is essential to boot computer. The MBR grabs the size and location of each partition on the hard disk.

mbr disk structure

As you can check on the image, the MBR consists of three parts:  Master Boot Code (Take 466Bytes), Disk Partition Table (Take 648Bytes), and the Boot Signature.

What Happens If MBR Gets Damaged

Because MBR belongs to your PC's startup system, your PC won't be running when your MBR is damaged. It holds the information of your disk partition.

Then how does MBR get corrupted:

  • Drive failures
  • Virus 
  • Malware
  • System shutdown

The error message of MBR:

  • Operating system not found.
  • Reboot and select proper boot.
  • Error loading operating system.
  • Non-system disk error

What you are going to do is to rebuild your MBR for re-using your PC. Don't worry. EaseUS Partition Master will help you rebuild MBR without data loss. 

Final Words about Fixing MBR

To sum up, we have shown the full guide relating to MBR. If your MBR is corrupted, you can try the two ways we introduced, the MBR repair tool and CMD.

To recommend the straight way, EaseUS Partition Master is the right one to rebuild MBR without CD and data loss. Get a free download in seconds. 

Free Download 

Windows 11/10/8/7100% Secure

P.S. If you have any problems with Master Boot Record repair, you can chat with our online service agent or send an email to [email protected]

Extra Tips to Fix MBR in Windows 

This part will continue to provide more questions and answers related to MBR in Windows. If you are interested, continue reading, and hope it can help you.

1. Will rebuilding MBR delete data?

Data loss won't happen unless you apply improper methods to rebuild it. Your PC might fail to boot because of the wrong operation. Check the best solution in part 1.

2. How to fix MBR windows 10 without CD?

Step 1. Restart your PC. Press Ctrl + Alt + Del. (If it doesn't work, repeat restart and press the button one more time.)

Step 2. The "Preparing automatic repair, Diagnose, Attempting Repairs" appears.

Step 3. Choose Advanced options.

Step 4. Troubleshoot > Advanced options > Windows startup setting > Restart

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Updated by Roxanne

Roxanne is one of the main contributors to EaseUS and has created over 200 posts that help users solve multiple issues and failures on digital devices like PCs, Mobile phones, tablets, and Macs. She loves to share ideas with people of the same interests.

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Written by Daisy

Daisy is the Senior editor of the writing team for EaseUS. She has been working at EaseUS for over ten years, starting as a technical writer and moving on to being a team leader of the content group. As a professional author for over ten years, she writes a lot to help people overcome their tech troubles.

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