My guess is the old driver is corrupted and still interfering. You can either delete the old driver or use system restore. Of the two, the easier thing to do would be to go to "system restore" and go back to a time when it worked previously. To get to system restore, in the Control Panel search box, type "recovery." Select Recovery > Open System Restore. Then if you can get it working, you can try updating again. If that doesn't work, Nvidia has a help forum also ... https://www.nvidia.com/en-us/forums/
I was just looking at it ... it seems like a lot of people have this problem!
