Boot From the Windows Install Disc
The first thing you’ll need to do is boot off the install disc, and then click through until you see the “Repair your computer” link in the lower left-hand corner.
You’ll need to choose the correct installation of Windows and then click the Next button.
And then you’ll get to the System Recovery Options screen, where you can get to the Command Prompt.
Repairing the Master Boot Record
If you want to restore the master boot record, you can simply type in the following command:
You can also write a new boot sector onto the system partition with this command (which is often more useful):
And of course, if you just use bootrec /? you’ll be able to see all the options.