[Full Guide] Bad Boot Sector Repair for Windows 7

You can learn bad boot sector repair in Windows 7 by following the guide. This article will share with you how to rebuild corrupted Master Boot Record and fix other boot issues.

Posted by @Irene December 17, 2024 Updated By @Irene October 18, 2024

What is boot sector?

The boot sector is a small section at the beginning of your storage device that contains important instructions for starting your computer's operating system. When you turn on your computer, the BIOS or UEFI firmware looks for the boot sector, executes its code, and begins loading the operating system. The boot sector is crucial because, without it, your computer wouldn't know how to start or function properly.

To help you better understand and repair the boot sector for Windows 7, here is a summary of the booting process: The BIOS or UEFI loads the MBR, which then finds the active partition, accesses its boot sector, and the boot loader in the boot sector starts the operating system.

Here is a brief explanation of the key terms:
  • MBR (Master Boot Record): Located at the start of a disk, before any partitions. It has two parts: the first 446 bytes contain the bootstrap code that helps locate the active partition, and the next 64 bytes form the partition table, listing all partitions on the disk. If you want to successfully boot, the MBR cannot be damaged or moved.

  • Boot Sector: Found at the beginning of the partition where the operating system is installed, it holds the boot loader code responsible for loading the OS. The boot sector remains in place, but the boot loader code can be modified if necessary.

  • Boot Loader: Located in the boot sector of the active partition, its job is to start the operating system. The MBR passes control to the boot loader, which then starts the OS.

Perform bad boot sector repair for Windows 7

When booting in Windows 7 with bad sector, you can try 4 easy methods. In this part, you can get the specific details.

Method 1. Fix bad boot sector for Windows 7 without disk

If you don't have a Windows installation disk, how can you repair the boot sector? Luckily, you can use AOMEI Partition Assistant to make the process easier. It lets you create a bootable USB drive and rebuild the MBR in a WinPE environment. Here’s how to do it, but first, you need to prepare a few things.

AOMEI Partition Assistant

The Best Windows Disk Partition Manager and PC Optimizer

Step 1. Insert the bootable device you created before to the computer with MBR errors, and boot the PC from the bootable device (You may need to change the boot order in BIOS).

Step 2. It will display the main interface of AOMEI Partition Assistant. Click the system disk, and select Rebuild MBR in the right toolbar.

Step 3. Select the type of MBR for the current OS.

Step 4. Finally, click Apply ->Proceed on the toolbar to execute the operations.

When the operation is finished, shut down the computer, remove the bootable device and boot your PC from the original disk.

Method 2. Repair damaged or missing BCD files in Windows 7

AOMEI Partition Assistant also offers Boot Repair feature for bad boot sector repair in Windows 7 as well. It helps fix damaged or missing BCD files, offering a simple solution to restore normal boot function. It is commonly used in scenarios like system boot failure due to missing or corrupted BCD files, boot issues after updates, conflicts in multi-OS setups, and boot sector corruption caused by viruses or other problems. 

Case 1: Repair an running PC

Step 1. Install and launch AOMEI Partition Assistant. In the Main Tab, please click the "Recover" tab and select "Boot Repair".

Step 2. The Boot Repair tool will pop up. Please click "Next" to start the system’s boot entries scan process.

Step 3. After the process is completed, it will display the scan result: system paths, system versions, and boot status. And, all repairable boot entries will be available to select.

Advanced Settings: Select a location to store the repaired boot entry.

Repair to the current disk: The system will boot from the current disk and ensure the boot files are complete and functioning properly. (By default)

Repair to another disk: This operation will repair the boot entry or create a new system boot entry to ensure the system can boot from the disk you select.

Step 4. Select one/multiple repairable boot entries you want to repair and click the "Repair" button to start the boot repair.

Step 5. Wait for the repair process to finish. Once it is finished, you can check the repair result. If it succeeds, you will get a "Repair Successfully" result.

Case 2: Repair Boot for PC that is unable to Boot

Step 1. Install and launch AOMEI Partition Assistant on a working PC, click "Recovr"-"Boot Repair" and then click the "create a bootable disk" option to create a WinPE "Boot Repair" disk.

Step 2. Plug the bootable disk you created into the target computer you wish to repair the boot issue.

Step 3. Enter BIOS in your computer, choose the bootable disk as the boot drive to access AOMEI Partition Assistant.

Step 4. The PC that cannot boot into WinPE will automatically load the Boot Repair tool and start the boot entries scan process. All boot entries will be displayed. Then you can follow the same operations as the above shows.

Method 3. Repair boot sector in Windows 7 with a Windows CD/DVD

How to repair MBR Windows 7? In general, the MBR repair requires the usage of a Windows installation DVD or CD. Now, let's get started...

If you have kept your installation disc, you can try to fix MBR in Windows 7 through Command Prompt. First please put your original Windows 7 installation DVD into the computer's DVD or CD drive. Then do as the guide below.

Step 1. Boot your computer from the Windows 7 installation DVD.

Step 2. When the message "Press any key to boot from CD or DVD… "shows up, press any key to boot from the DVD.

Step 3. Select a "language", "keyboard layout" and click "Next".

Step 4. Select the operating system and click "Next". In the "System Recovery Options" window, click on "Command Prompt".

When Command Prompt successfully launched, type the following commands and press enter each time:

▪ bootrec /rebuildbcd▪ bootrec /fixmbr▪ bootrec /fixboot

Remove the installation DVD from the disk tray and restart your computer to check if it can boot up successfully.

If the above commands do not work, you can run the following command to export and erase the BCD store and use the Rebuildbcd command again to fix MBR Windows 7. bcdedit /export C:\bcdbackup ● c: ● cd boot ● attrib bcd -s -h -r ● ren c:\boot\bcd bcd.backup ● bootrec /rebuildbcd

Method 4. Fix bad boot sector in Windows 7 with Command Prompt

You can also fix master boot record (MBR) by getting into Windows Recovery Environment (Windows RE). 

Step 1.  Get into the Windows RE. Some computers have a special recovery partition that allows you to start the Windows RE by pressing a special key directly without needing a physical disc. If your PC doesn’t have one, you can use a Windows installation disc to get into Windows RE.

Step 2.  When you see the initial Windows installation screen, click "Repair your computer".

Step 3. Windows will then load the recovery environment. Here you need to click “Troubleshot” option. Then, you will get into the Advanced Options page.

Note: Here, you can run Startup Repair first to see whether it can fix problems that keep Windows from loading. If the repairs were successful, you’ll be given the option to restart your PC or return to the Advanced Options page. If it tells you that “Startup Repair couldn’t repair your PC”, you can try repairing the Master Boot Record or rebuilding the boot sector from the Command Prompt as the following.

Step 4. Click Command Prompt, type Bootrec.exe, and then press Enter. In that case, you can use the following instructions, which should work for you.

  • Bootrec.exe /FixMbr: Fixes MBR corruption or removes nonstandard code from the MBR.

  • Bootrec.exe /FixBoot: Writes a new boot sector compatible with your Windows version, useful if the boot sector is damaged or replaced with a nonstandard one.

  • Bootrec.exe /ScanOs: Scans all disks for Windows installations not listed in the Boot Manager menu.

  • Bootrec.exe /RebuildBcd: Scans for compatible Windows installations and lets you add them to the BCD store, useful for rebuilding it completely.

You can then type bootrec /? for more options and help. Please be cautious as these actions cannot be undone and might cause issues if used incorrectly.

Conclusion

Bad boot sector repair for Windows 7 can be effectively fixed with the help of AOMEI Partition Assistant. After successfully resolving this problem, you can also use it to install SSD in laptop without reinstalling the system step by step, extend drive space, manage partitions effectively, and so on. If you are a Windows Server user who want to repair boot sector, please choose the Server edition.