Do you see any error code showing on your screen while turning the Toshiba on? If the screen works normally /doesn't turn black/ in safe mode, then the driver for your video chip on the mother board went corrupted.
If you are able to get a recovery disk, it would be great. If you are running Windows, I think Windows Repair CD would help.
If you are able to log into Safe Mode, try scanning your machine with different anti-malware and anti-virus programs.