Computer locked up or frozen?
Rule #1: Don't hit it or shake it.
I know it may make you feel better, but you will not be doing the computer any good. Plus you could damage the hard drive to a point where data recovery will be impossible.
Rule #2: Find out why did the computer crash?
If you've recently made any hardware changes, or installed new software, either of those could have lead to your current computer freezing or slowing down. Shut your computer down and remove any new hardware then try to reboot. To remove faulty software, boot into safe mode and then use the control panel to uninstall.
Computers will also shut down temporarily due to overheating and re-boot again after the system has cooled. But, be very careful if it.s due to overheating because overheating will cause hardware damage. To avoid overheating, always keep the computer in a room with proper ventilation.
Rule #3: Use System Restore
If you are still having computer freezing, reboot the system in safe mode and use the Windows system restore option to restore the computer to an earlier date.
Rule #4: Use Virus Protection
Viruses are also known to cause computer freezing and crashes. We recommend Microsoft Security Essentials for home users. It's free and works as good as any other product. For businesses we use Vipre Security.