Sounds like windows applied an automatic update that was incompatible. Try booting into safe mode and using system restore or using the advanced boot options to restore to a previous restore point.
http/www.7tutorials.com/5-ways-boot-safe-mode-windows-8-windows-81
Once you boot into windows using safe mode, do the following to restore to an earlier point in time:
To restore your PC to an earlier point in time
1. Swipe in from the right edge of the screen, and then tap Search.
(If you're using a mouse, point to the upper-right corner of the screen, move the mouse pointer down, and then click Search.)
2.Enter Control Panel in the search box, and tap or click Control Panel.
3.Enter Recovery in the Control Panel search box, and then tap or click Recovery.
4.Tap or click Open System Restore, and then follow the instructions.