By AOMEI / Last Updated October 22, 2020

Introduction of MBR

MBR (short for Master Boot Record) is a special type of boot sector at the very beginning of partitioned computer mass storage devices. It will be created when you create the first partition on the hard drive. MBR contains the Partition Table for the disk and a small amount of executable code for the OS startup. Without a valid MBR, it’s impossible to boot the system from the primary hard disk.

MBR does not belong to any operating system and it cannot be read through disk commands provided by operating system. But it can be modified and re-written through the command. MBR may be affected by malicious code, become corrupted by disk errors, or be overwritten by other boot loaders when experimenting with multiple operating systems on a host. Those viruses and programs can usually cause MBR corruption. Thus, you will need a MBR repair tool.

When do you need to repair MBR?

Master Boot Record (MBR) belongs to boot record, along with Boot Configuration Data (BCD). Sometimes you may get the error message like “Operating System not found” or “System missing”, and you may not able to boot your system at all. Such errors are most likely to be caused by damaged MBR. At this time, you need to rebuild or repair corrupted MBR in Windows 10/8/7 to fix the issues. Mostly, the MBR problem may be caused by malware infection, or improper shutdown. Some external hard disk may also encounter corrupted MBR.

How to repair MBR in Windows 10/8/7?

Here we provide you two effective ways to repair MBR as the following content shows.

Method 1. Repair MBR via Windows Installation Disk

If you have a Windows installation disk in hand, you can repair MBR of the drive easily.

1. Connect the external disk to your computer. Shut down the machine and insert the installation disk. Then boot from the disc.

2. Select time, language and keyboard input, click next.

3. After that, click Repair your computer in the lower-left corner.

4. Press Shift + F10 key combination to call out Command Prompt.

5. Type the drive letter of your external hard drive partition at the prompt, like F: , followed by a colon and press Enter.

6. Type these commands in sequence and press Enter after each.

  • Bootrec /fixmbr

  • Bootrec /fixboot

  • bootrec /scanos

  • Bootrec /rebuildbcd

Fix Mbr

7. Restart the machine when it completes.

Tip: If Windows falls to the internal disk, you’ll need to change boot priority to the installation disk in BIOS.

Method 2. Free download a professional MBR repair tool

In addition to repairing MBR via Windows Installation Disk/Command Prompt, you also can use a powerful third party MBR repair utility to repair the damaged or corrupted MBR. Here I highly recommend the free partition manager named AOMEI Partition Assistant Standard. This freeware provides many powerful functions like rebuild MBR, clone hard disk, clone partition, convert MBR to GPT/GPT to MBR without deleting partitions, etc.

With the feature Rebuild MBR in AOMEI Partition Assistant Standard, you can easily repair damaged MBR within simple steps. Below are the specific steps:

Before you do:

Connect the hard drive to a working Windows PC which installed AOMEI Partition Assistant (you can download AOMEI Partition Assistant Standard free from its official website).

Use AOMEI Partition Assistant to create a bootable media (USB, CD/DVD).

Make Bootable Media

Insert the bootable device you created before to the computer that its MBR is damaged or corrupted, and boot the computer from the bootable media. It will get into the main interface of AOMEI Partition Assistant Standard automatically.

Note: Steps to boot computer from the bootable media

1. Connect the bootable media to your computer, and start your PC.

2. When you see the PC logo, tap a BIOS key to enter BIOS setup.

3. Under the Boot tab, set the bootable media as the boot drive. Then save the change and restart your PC.

Step 1. Right-click the disk which need to be repaired and select “Rebuild MBR” in the pop-up window.

Rebuild System Disk MBR

Step 2. In the next window, set the type of MBR for the current OS. (Choose a proper MBR type according to your operating system.) Then, click “OK” to continue.

Choose MBR Type

Step 3. After that, click “Apply” on the toolbar to commit Rebuild MBR operation.

Apply

Notes:
◆“Rebuild MBR” is a lossless data operation, but improperly rebuild MBR may cause your computer unbootable. So, you’d better learn more relevant knowledge before you do this operation.
◆“Rebuild MBR” only can solve problems such as corruption of the MBR code. It cannot solve the problem that the operating system cannot be booted due to the loss of bootable file or system file.

Conclusion

With the free yet powerful MBR repair tool, you can easily and effectively repair your damaged MBR in Windows 10, 8, 7. Besides repairing MBR, it is also able to help resize partition, move/create/delete/merge/format partition, migrate OS to SSD, convert data disk between MBR and GPT partition styles, convert file system between NTFS and FAT32 without formatting and so on. If you want to repair MBR in Server 2019/2016/2012/2008/2003, you can try AOMEI Partition Assistant Server.