Try starting in "Safe Mode" and see if it will load. Granted it would have restricted access, but if it loads, then there may be something on the computer that is prohibiting it from loading normally. Virus, malware, etc. You would then have to remove the problem before you could use it normally.
How to enter "Safe Mode" when booting the computer.
In Windows 8 and 10...
As your computer restarts, press F8 (possibly a few times) to enter "Safe Mode"
a. Press the "F4" key to Enable "Safe Mode".
(The computer will then start in "Safe Mode" with a minimal set of drivers and services.)
b. Press the "F5" key to Enable "Safe Mode" with Networking.
( Once "Safe Mode" with Networking starts, Windows is in Safe Mode, with additional network...