Try seeing if the computer will boot up completely in "Safe Mode". If it will, then you have something on it (program, malware, virus, etc.) that is hindering it from loading completely outside "Safe Mode" and you would need to remove that.
Also, if you just updated anything or installed anything right before this started, those should be the first changes you 'undo' to see if it gets resolved.
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...