Yesterday I tried updating my drivers to the latest Nvidia ones (the ones optimized for Oblivion) and the first thing I did was deslete my old Nvidia drivers. It asked me to restart after I uninstalled them, so I did. On restart everything seemed fine, POST looked normal, and it went into the Windows loading screen normally too. But after the Windows loading everything went black, and did not come back. I have also tried booting in every safe mode, and VGA mode, and for safe mode, after all the text fills the screen, it just stays like that, stopping and becoming frozen on "giveio.sys". For VGA mode, it goes black after the Windows loading screen.
If VGA mode doesn't work, I only have one suggestion. Try doing a repair installation of windows, where you just reinstall windows over the old installation. That should reset all of the drivers to the windows defaults. You will have to reinstall all of the windows patches and updates as well, but if VGA mode doesn't work I don't know what else you could do.