If there are no important documents stuck behind the password (that you can't access by plugging the hard drive into a different computer) then I personally would back up anything important and blank the drive then reinstall windows from scratch
.
You don't need an array of AV to avoid viruses. The number one protection against computer viruses is user knowledge. If you don't click dodgy links, follow dodgy phonecalls, or visit dodgy websites then the basic, free AV protection that comes with windows is more than enough. I haven't used 3rd party AV for more than a decade. I've
never had a virus. And I torrent
.
Basically they're relying on ignorance... be skeptical and don't install anything you don't recognise and your PC will be fine.