Help with black screen with blinking gray cursor "-" dash dell m1530

Please anyabody. I cant get even get through to the windows logo. I think its because of a virus that I was having it was "windows vista security". I was just sufring the net then the computer automatically restarted and cant even get through the windows boot logo. I cant safe mode i cant go to the last known config and any other options. I dont want to reformat I dont want to lose my files they are very important. I cant find the windows repair because I do not have the original windows vista cd but i dont have someone's windows vista cd. Please help i dont know what to do.

Edit:
I have been trying to use the recovery disc and set the boot sequence to CD when im trying to use the CD. I put USB to first boot sequence when i use the usb since the i already put it in. When i try them the laptop just restarts instead i supposed to see a "press any key to continue". I think there's a problem to thge motherboard because the motherboard was already been replaced and the lady found a screw and she doesnt know which screw it was supposed to be at after building the laptop back as it should be. That day the laptop was working but a couple of months the laptop was having some blue screens it restarts to itself hangs up and do a loud repeating broken audio sound. Please help I dont want to lose all of my files.