although you don't know what your last drivers were, your computer does.
Using the driver wizard/Device Mgr.(?) you should be able to roll back to previous version 1 device at a time by using roll back button.
Best of luck (changing drivers scares the bejeebers out of me)!!!
For what little it may be worth.
The situation is this, I went ot the Nvidia website and did a scan of my pc where it identified me as having a NVIDIA GEFORCE 6800 SERIES GPU, and recommended that I download and install driver 163.71, I also clicked on the motherboard link to upgrade drivers, but I cannot imagine that the motherboard driver will have been installed on my PC, as I subsequently learned that I do not have an Nvidia motherboard but an ASUS A8N-SLI PREMIUM board!!! I have messed up reral time as now all my media players installed on my PC playback my movies with strange colours,(ANDY WARHOL STYLE!!!) and or some of the films do not have sound, all very bizzare, my divx player plays back some of my films without problem and then some with problems? CAN ANYONE HELP????? I guesss I need to 'roll' back to my previous drivers, but I do not know what my previous drivers were? would the drivers for the graphics card be on the software disc which came with my graphics card, if I received such a disc, will have to check and see?