go into control panel, click on system icon, click, hardware tab, click device manager, click display adapters, double click your nvidia graphics card, click Driver tab. click rollback driver, follow instructions there.
or, go to start, all programs, accessories, system tools, and select system restore, select a date before you put the new driver on, and click go, let it do what it needs, reboot and see if it works.
or, get a technician to look at it, scratch his arse, have a cup of tea and charge you for it
although, i strongly advise you dont try any of the above suggestions unless you have some sort of clue whats happenning, or can afford to buy a new computer
