Unless you're an ancient Roman, experiencing a sense of envy or jealousy, you've not got 'invidia'!
(Sorry, Latin joke!)
NVidia is the name of the company which manufactured the graphics card which you had installed. By setting the registry back to a date before the installation, you've effectively uninstalled the driver software associated with the new card.
Solution No.1:
Go into System Restore again, and look for the option to 'Undo System Restore'
Solution No.2:
If you've got a disc which came with the new board, use it to reinstall the missing driver. (You'll need to restart your PC before it will kick in).
Solution No.3:
Identify the graphics board, download the appropriate driver and install it. (Again, you'll need to reboot afterwards). You MIGHT be able to identify the board from Control Panel ->Performance and Maintenance ->System ->Hardware ->Device Manager->Display Adapter (and clicking the + next to 'Display Adapter') but I'm not sure whether that method will work, as I think that it might draw upon the graphics driver (which is no longer installed) for the information.
Otherwise, a free program called AIDA32 can examine your computer for the relevant information:
http://cr.am/framed.p...3D183&ref=driverguide
Then you can download the required driver from here:
http://www.nvidia.co....index.aspx?lang=en-uk
Chris