Windows is usually good about rolling back a failed update but sometimes it does go very wrong.
Are you able to access the troubleshooting screen when rebooting? If so, you can try the automatic repair tools in there including system restore. If that fails, you can access the command console (I think in advanced menu of the troubleshooting screen) and run sfc /scannow. Then run DISM to repair the corrupt files.
Googling either of those commands should give you some step by step guides on how to run them from the startup troubleshooting screen.