Four suggestions:
1. Back to your latest image backup (if you made one).
2. System restore from the recovery console after booting from a disc or stick you make with Microsofts Media Creation Tool (assuming you have Windows 10 or a retail version of Windows 7 or Cool.
3. Use the recovery media that came with your computer or that you were invited to make when you first used it to go back to factory conditions.
4. A fresh install of Windows on a new hard drive. Then copy your files from the old drive before formatting it to get rid of the malware.

It's a good idea to make a backup of your files you don't yet have a backup of, by copying them to an external hard disk after booting from a Linux disc or stick (free to make).