Hello
I know you have probable done this before but the first thing to do is...
Run a full up-dated AV scan with your installed AV...
Run a full scan with malwarebytes, free version.
Malwarebytes
After you know that there is no problem as far as a virus or malware then do a sfc scan, here is the tutorial for doing so.
System Files - SFC Command
When the sfc is done look at the results, if there are any error's then run the sfc 3 more times each time you run it , it repairs more. This is the easy way...
1. Click Start...
2. Type CMD in the search box...
3. When to popup list comes up go to the top and Right Click the cmd.exe and run it as administrator...
4. When the command box appears then type sfc /scannow, notice the is a space between the sfc and the forward slash...
If your sfc won't run in reg mode the run it in safe mode. When you run the first sfc upload it to the forum so we can see what's going on.
If you have questions or need help then post us back and we will help...