Do you have access to a windows 8, 8.1, or 10 install usb/disk?
I have booted from those before, then used the repair option on the second screen. A startup repair from there might work.
You might need to acquire an external optical drive for a disk, of course.
Have you tried also using program in command prompt? Sfc perhaps?
I have found that normally the issue you're experiencing is related to explorer.exe not working correctly.