You've done all the things you should've, so you may have to restore to factory settings. If you had a system backup on an external hard drive, you could restore from that, but I take it you don't have a backup. One thing you could do is to check for corrupted system files. Open an administrator command prompt and run SFC if the above doesn't help. Click START, then type CMD in the search box, right-click CMD.EXE and click Run as administrator. Then from the command prompt type sfc /scannow.

When you've gotten your system back like you want it, I urge you to get yourself an external hard drive and a good 3rd party backup program. You can set it up to do everything automagically at the time and frequency of your choice. 1 TB external hard drives are about $70 these days and a really good FREE backup program is the Easeus todo backup free which you can download from . That can save you a lot of time and frustration the next time something like this happens. Sooner or later it happens to all computers for one reason or another.
Good luck.