What version of Windows do you have?
Try when powering it up, if you can see the BIOS screen, *Which apparently you can*, smash either the F6 key or F2/F12/whatever your unit's boot menu is assigned to. If you can't see this, it sounds like a driver went bad. Fixing black screens during a start up is a...like a hit or miss, either you fix something then something else breaks, or you simply don't get to it at all and you'll have to either use another OS, like Ubuntu to go into the Windows partition and mess with some files, or use your Installation disc and see if you can get the Repair Option to pop up.
If all else fails, then simply wiping the HDD or the Windows-specific partition is probably the last resort, but you'll lose all your goods unless you use Ubuntu to back em up.