Are you using onboard video?
If so, get a hold of a PCI (or PCIe) video card & try it.
If you already have a video card installed, try a different one.
Your motherboard may have just taken a dump.
if you don't have money for a new PC, you can search ebay for an exact replacement motherboard (they're usually inexpensive for older PC's).
. . . or take this opportunity to upgrade your PC
