Windows 10 forced update broke my computer

I don't know what to do.
I can't reformat this laptop. I have a piece of software on it that is the only copy I have, & only works because I was logged in when they got rid of it and forced everyone to go with the newer version I don't want. Not to mention it has all of my info on it in offline mode.

1. I didn't realize the update affected my external HD which has all of my files on it until I tried to play some music & it kept spinning. Then I started to get a popup saying it needs to be formatted. OMG. I plugged it into my desktop that has Win 7 on it & it also wants me to reformat it. WHY??? What did Windows do to it?
2. I had to restart my laptop 5 times before the Open shell would load & it takes forever to load.
3. It broke my Thunderbird, but now I know why my emails never loaded, it's because it can't get access to my external HD.
I can't believe this. I don't know what to do & no, I don't have a thumb drive with the restore point thingy on it. I needed that, didn't I?
But how would that fix the external HD?