I'm assuming you are using Windows. The easiest way to rollback the drivers is in device manager, double click the NVidia display adapter and under the drivers tab, click roll back. You need to be logged in as an Administrator to do this though.
After doing this the window will be unresponsive for a minute or so, and then the old drivers should be installed.
If this doesn't work you can also boot Windows in safe mode, and remove and reinstall the drivers from there.