re: Windows Defender

The machine can almost certainly be saved, especially if you have a backup. Do you?

Even if you don't, most viruses do not infect data files - only the executables. So another possibility would be to transfer the data to another drive and do a clean reinstall of Windows. Then install MalwareBytes, then reinstall all the software you had, then move the data back. It can be a bit involved though if you've never done that before.

That's actually what I do myself, with preplanning and a practice run or two it's actually pretty straightforward and takes much less hassle than trying to clean an infected system. But if you've never done it then it may be easier to just get a replacement for $400 or so, copy your data, and move on with life.