Windows won't start

First Step is to Press F8 at startup to try System Repair or choose last Known good configuration.

If you find Windows won't load, pop your Windows installation disc into the drive and restart your computer. Then select to boot from CD when prompted. Pick your language, click Next, and then choose "Repair your computer".

Windows will attempt to detect your installation – if it's successful, click "Startup Repair" to enable Windows to try and fix the problem. The repair isn't always successful the first time, so if Windows still won't load try the process again to see if it can now resolve your issue.