If you know your BIOS password, or it isn't set, you can press <del> at startup and get into the BIOS, then there should be an option straight away to restore the default BIOS settings. Under any circumstances your screen should work when you access the BIOS - if not then check the cables, check the monitor, then think about the graphics card.
Depending on your system, a BIOS reset will usually work straight away. Older systems need to be tweaked a little, but newer systems are a bit 'smarter' and auto-detect nearly everything. If in doubt, don't play about, but at the least try to access the BIOS by pressing <del>. You should see something on the screesn
HTH
Tels Win2000 Network Administrator