logged out of PC and had updates to install, okay-ed the updates. When I tried to open my files the next day they were corrupt. When I tried to open the sames files from my back-up they were also corrupt. We were having power surges a few days ago when I was working on the files but there was no indication that anything was wrong at that time.
And what got this problem to do with LibreOffice, if you installed updates (which one is unclear, thus assuming from your description these were operating system updates [Windows?]) and then you end up in some unspecified corruption.