When the computer first starts up, and you hit that black screen with the white text (usually), hit either delete or F1-F4, and you should come up to the BIOS Screen. You should be able to find your way through BIOS; usually it's not that complicated if you use a brand name computer (a little more complicated when if you build it).
Boot with safe mode, or vga mode ,, and use Driver Cleaner pro , and remove nvidia and choose all filters remove them all. Then reboot and install some official forceware drivers, gl,,,