Try booting in "Safe Mode" and see if it will completely load. If it does, then you need to figure out what is on the computer that is causing it not to load in "Normal" mode. It could be a bad program, virus, malware, etc. If it still won't load in "Safe Mode", then you may have to do a system repair or worst case a system restore.
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...