Please help..

Suddenly my LCD monitor is showing out of range error. I can't fix it because after showing bios and boot menu it turns out of range. I am unable to boot into safe mode either. I have windows 7 and windows xp installed. Can not boot any of them.

My on board display is intel and that works but my graphic card display is not working. It is NVIDIA 5600 DT 256 MB graphic card. How to fix ?