hacked

A lot of the good extortion programs damage the installaions of AV and anti-malware software. I agree that you should boot into safe mode, but from there, run the system recovery, and choose a date from before this extortion message started popping up. Once it has restored to an earlier version of the registry, install Malware Bytes, and run a full scan. It should remove the files associated with the bad program. After that, install or reinstall the AV software of your choice. I do this all of the time. Let me know if you need more detailed instructions.