What actually happened? There are a few possile reasons for the computer just powering off
1. Power supply has gone. if this is the case, a new power supply Compatible with the power supply in the case can be bought. they are not hard to install.
2. Your CPU is either overheated or burnt out. Overheating could be caused by a dusty and clogged CPU fan (I have just dealt with a similar case). if this is the case, the plastic blades between the fan that protects your processor have to be cleaned (CAREFULLY, otherwise you could end up with a broken processor fan.
3 Your hard disk has gone. New hard disk required.
4 Controllers on your motherboard have gone which requires a new motherboard.
The list goes on.
Try this:
Try a new plug into your computer, it could be as easy as the fuse has gone in your power lead. (Test with the lead from your monitor.)
Unhook ALL connections from the power supply to your hard disk, cdrom drive and any other drives you may have connected to the power supply . Watch for the fan at the back of the power supply. If that turns and the light shows on the motherboard, then connect the hard drive to the power supply. If the hard drive still does not boot up, you may be looking at a hard drive problem.
Other options:
Go into BIOS on your PC and change settings to boot from CD drive only. Place your windows CDrom into the CD drive and boot up. You will be given options. Initially, choose the repair option. If this doesn't work, try re-installing Windows this will format and re-install BUT in the next 2 cases ALL data and drivers,apart from the Windows drivers will be lost. Send back reply I will be watching. OR
Last Scenario
Back to formatting, if you want to take this option, if you have a floppydrive, get hold of a windows 98nd edition recovery disk, place the floppy into the floppy drive, boot up and choose the option boot with cd rom support. Try re-installing your windows system and see what happens. Ifno success, get back, you may have to clean your disk and reformat.
Try and let me know