Wow. I just answered another question with the identical answer:
Reboot and select Safe Mode in the advanced boot options. Within safe mode you can implement a restore point.
Getting into safe mode in previous versions of Windows was a very straightforward and relatively easy task to accomplish, just press F8 at boot to get to the advanced boot menu.
In Windows 8 it is a royal pain in the ass to get to such a crucial part of Windows. Microsoft wants you to believe that it is because Windows boots too fast now - complete utter bull-shit. It is because Microsoft believes that you shouldn't be able to have access to such things when their beautiful work of art is just so damned pretty and designed so insanely well and anyone trying to get to safe mode doesn't know what they are doing. Here is Microsoft's instructions on how to get to safe mode when their POS is broken: