How to Fix an Invalid Partition Table

By Mike Venture

All computer data is stored on drives, most commonly hard disk drives. These drives are divided into sections called “partitions.” Most computers have one partition per hard drive. Each partition is treated by the operating system as though it were a separate drive. The properties of each drive’s partitions are stored in a special file called a “partition table.” If the partition table is damaged or missing, the drive will not function properly, and if the drive has the computer’s operating system installed on it, the computer may not boot. Follow these instructions to access Windows 7’s built-in partition repair tools.

Step 1

Disconnect or remove all removable or external drives.

Step 2

Restart the computer.

Step 3

Wait for the BIOS status screen to appear. The screen will either have the logo of the computer manufacturer (such as Dell) or be black with white letters and many technical details.

Step 4

Press and hold the "F8" key as soon as the BIOS screen disappears. The Windows "Advanced Boot Options" menu appears on the screen.

Step 5

Select “Repair Your Computer,” and then wait for the Windows 7 Recovery Environment to load.

Step 6

Select your keyboard layout from the drop-down box.

Step 7

Log in using an administrator account, if necessary. The “System Recovery Options” window appears.

Step 8

Click “Command Prompt.”

Step 9

Type “bootrec /fixmbr” without quotation marks.

Step 10

Wait for the process to finish and restart the computer to see if it worked. If it did not work, repeat steps 2 through 8, then continue to the next step.

Step 11

Type “bootrec /fixboot” without quotation marks at the command prompt.

Step 12

Wait for the process to finish and restart the computer to see if it worked. If it did not work, repeat steps 2 through 8, then continue to the next step.

Step 13

Type “bootrec / RebuildBcd” without quotation marks at the command prompt. If the command is not successful, it’s likely that the disk is not recoverable and you will have to format the disk and reinstall the operating system.

Tips & Warnings

  • If the “Repair Your Computer” option is not available, you will need to obtain a Windows 7 disc from the computer’s manufacturer. Alternatively, you can download the recovery disk image file from the link in “Resources” and burn it to a blank CD on another computer.
  • If you have a dual-boot system running two different operating systems (i.e. Windows and Linux,) using the "bootrec /fixmbr" command may make it impossible to select an OS on startup. Therefore, before trying the "bootrec /fixmbr" command, use the "bootrec /fixboot" to fix the partition table for a specific partition. The "bootrec /fixmbr" command rewrites the master boot record for all partitions on the hard drive.