I am totally dumb about this sort of thing--but the first thing I tho't of was to do a ''restore'' to an earlier time. Recently, my entire folder of designs disappeared from a laptop..along with other info. I was devastated! I tried everything I could think of, including 'restore'. Shut down, walked away, and next time I turned on the l-top...it was all back. I am still confused about where it all went. Fortunately, I had most of the missing info stored in another computer ....but....it still made me very distraught!
I could not comment here as to what I would like to do with these evil types. Not only do we have this with private hackers but most national Governments are at it as well! I do hope that you manage to get things sorted soon.
Unplug the other from the internet. Take it to a computer professional for help. Check with your bank and any other online services to make sure they were not compromised.
I am so sorry you are having trouble!
Send me a PM if you think I can help y