Hopefully you have the original operating system disk. Boot it from the CD drive before starting windows, select repair install without reformatting the hard drive.
After your operating system re-installs, delete the old video drivers before installing the nvidia drivers, if needed. The system may have been corrupted by a microsoft update. It is advisable to shut off microsoft update to avoid any more unwelcome surprises in the future. Then back up all your files in case this happens again in the future. If it does happen again, do a fresh install, reformat the drive, re-install your files from your back up, shut off, don't use microsoft updates.
The best test: I put the HARD DISK in a absolutely different machine, with different motherboard, different chipset, power supply, etc and I GET THE BLACK SCREEN.
Actually, I think that's the very worst test. A different PC will require different drivers, so the chances of it booting from your hard disk are very slim.
You've already located the cause of the problem (if you disable the graphic card it works). Boot up with the graphics card disabled, remove all drivers, reboot and install the correct driver. If that doesn't work it could be that your graphics card is broken.
Alternatively, if you let people know details of your hardware (in particular m/b and graphics card) it may be possible to give a meanigful answer.