Using a clean computer, download and store several versions of RKILL to a USB drive. Also download a copy of Malwarebytes.
If your computer actually boots then it's likely just hidden your files. On your computer boot to safe mode and run RKILL, then w/o rebooting install and run a full malwarebytes scan (that may take several hours if you have a large hard drive). Unless it is a particularly persistent piece of malware that should remove it but you may then have to go in to remove hidden &/or system attributes from all your files/folders.
If the malware remains then you will need the name ... usually screens keep popping up trying to sell you a remover - that is the virus so get the name of what it wants to sell. Some of those require you download an additional program to try to stop it.
Find links to RKILL & Malwarebytes in our
Freeware DB