This is generally most useful if you’ve broken something and there’s a boot loader error, or if you have made the mistake of installing an older version of Windows on the same PC that already has Windows 7 which wipes out the boot loader.
Note: If your PC starts booting into Windows but fails, you should probably try using Safe Mode instead.
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.

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