If you have Windows 7 boot problems, the boot sector or master boot record on your system partition may be damaged, corrupted, or has missing files. And you will receive an error message like the following before Windows actually begins to load.
Error loading operating system
- Missing operating system
- Reboot and select proper boot device
- Invalid partition table
- Bootmgr is missing
- FATAL: No bootable medium found! System halted.
Then, what are the boot sector and master boot record exactly?
What are the boot sector and master boot record?
The boot sector is a small section at the beginning of a hard drive. It's created when you format the hard drive.
The boot sector contains some code and data that helps BIOS hand off the startup process to Windows. It also hosts the Master Boot Record (MBR), which contains the disk signature, partition table for the disk, and a small bit of code called the master boot code.
When a PC starts, the BIOS will load the master boot code into the PC's RAM. Then it will scan the partition table, determine the active partition, load a copy of the boot sector into the PC's RAM, and hand off the startup process.
Learn how to run Windows 7 boot repair when the boot sector or master boot record is damaged from the next part.
Three efficient ways to run Windows 7 boot repair
Startup Repair with Windows installation media
Boot from Windows installation media
If your boot sector or MBR runs into problems, you cannot start Windows normally. That's to say, you need to create the Windows installation media and boot from it.
Start with the detailed steps:
Step 1. Create Windows 7 installation media on a working computer. You can download ISO image files from Microsoft Store and burn the ISO image files to a USB drive or CD/DVD via Windows 7 USB DVD download tool.
Step 2. Plug the USB drive into your computer.
Step 3. Start your computer and press the corresponding key to go to BIOS.
Step 4. Set boot priority to USB drive in the Boot option.
Step 5. Restart your computer and press any key to boot from USB flash drive.
Step 6. Wait for Windows 7 installation files to load.
Step 7. Click Repair your computer in the initial Windows installation screen.
Step 8. Select the operating system in the window and click Next.
After that, you can select the operating system you want to repair and it will automatically run Startup repair and try to fix the problems it finds. Also, you can choose to run startup repair manually.
Run Windows 7 startup repair manually
The startup repair can fix the Master Boot Record or recreate the boot sector. And it will scan for and try to fix other common startup problems as well.
The specific steps:
Step 1. Click Startup repair in the System Recovery options
Step 2. Now, Startup Repair will try to find the startup problems and repair it. You just need to wait.
Step 3. After the operation ends, you can click Finish to restart your Windows 7. But If the startup repair not working in Windows 7, you still can click View advanced options for system recovery and support and back to the System Recovery Options page.
Windows 7 boot repair via Command Prompt
Step 1. Click Command Prompt in the System Recovery options
Step 2. Fix MBR in Windows 7. You can type the following command and hit Enter.
Note: This command can write a new Windows-compatible MBR based on the version of your Windows to the boot sector. And it does not overwrite the existing partition table.
Step 3. Repair boot sector in windows 7. You can type the command below and hit Enter.
Note: This command can write a new boot sector to the system partition. And it does not overwrite the current partition table. If you install multiple operating systems on this computer, you need to reconfigure the boot options.
Step 4. Fix bootmgr is missing in windows 7 via command prompt. You can type the below command and press Enter.
Step 5. Rebuild your BCD and get the missing Windows installations back. You can type the following command and press Enter to run it.
Step 6.Rebuild the boot sector for Windows. You can type the following command and press Enter to start it.
bootsect.exe /nt60 all /force
The /nt60 parameter applies the master boot code that is compatible with BOOTMGR. The /all argument updates the master boot code on all partitions.
The /force parameter forcibly dismounts the volume(s) during the boot code update so that the Bootsect.exe tool does not gain exclusive volume access.
Rename and rebuild BCD via Command Prompt
If the above command prompt does not work for you, you still can try to rename BCD first and then rebuild it via CMD.
Step 1. Type notepad in the command prompt.
Step 2. Click File > Open > Computer, find the file BCD in the correspoding drive, rename it as BCD.old, and then save the change and exit this window.
Step 3. Type bootrec /rebuildbcd in the command prompt window and input Yes when prompt.
Step 4. Type bcdedit /enum all in the window.
Step 5. Type exit and reboot your computer.
Extra tips for Windows 7 boot repair
1. Scan the integrity of your file system and hard drive via Check Disk utility.
Aside by problem of boot sector itself, the physical problem of your hard drive can also damage the boot sector and MBR. Thus, you need to rule out this possibility.
2. Backup your computer with a free backup software.
No one dares to say that you can recover your computer all the time. Once the recovery fails, you can only reinstall your computer and all the apps. What's more, you will lose your files forever. Thus, you need to create a backup for your computer or files. With one or more backup in hand, you can restore it whatever happens. To backup your computer, you need a proper software. I recommend you AOMEI Backupper Standard.
With this software, you can backup system, disk, partition, even a single file. You can use email notification to get to know whether your backup is completed successfully or not. Also, you can create a Windows 7 schedule backup at an interval date, such as daily, weekly, monthly.
And you can manage backup disk space via Backup Scheme. But this feature is only available on the paid-version. If you want to free up disk space, you need to upgrade to AOMEI Backupper Professional. If you use server-based computer, you can directly download AOMEI Backupper Server edition.
To backup your computer, you can download the backup software and open it. Then, click Backup and select the Backup type in the list. At last, follow the corresponding article to finish the backup.
To restore your backup, you can click Restore and complete the rest of step via on-screen instructions.
When you cannot boot your computer owing to boot sector or MBR, you can use installation disk to run Startup Repair or run Windows 7 boot repair via Command Prompt. But you cannot recover your computer every time. You'd better take some measures in advance. Backup is one of the best measures, which can restore your computer all the time.