Hi Joe,
First of all, you should always tell us the make and model, what operating system you are using and if you've added some new part, whether inside or outside to your pc.
Also is it a laptop or desktop?
In the meantime, if you can hear your pc running, then perhaps it's the monitor thats not working.
Try if you can, plugging in another monitor.
If that works then your own monitor is gone. If not......
Check if all the fans are working. Pc's need to be kept cool and away from closed in desks etc... When they over heat they shut down. The cpu fan is important as it keeps the processor cool.
Also don't rule out a virus. Is your antivirus software up to date and running?.
If a virus is shutting down your pc, then you may have to take out the hard drive to clean it on another pc.
If your running windows (2K, XP or vista) follow simple rules.
-Keep firewall on. Keep antivirus up to date.
-Don't run two antivirus software at same time. 1 only.
- Allow automatic updates as some are patches.
Try these for now and see how you get on.
Good Luck.
Anne, October 2008