Try searching for the files using Windows search feature.

Maybe they somehow did not end up where you expect.

Also refreshing the file explorer window with f5 sometimes seems to help. But that’s probably not going to help you as you say you already opened the explorer window to your new folder *after* copying the files.

You could try other things. Go to where you think the documents ended up on the c (or whatever) drive and check the properties. Does it show space used by the folder? If it says “0 bytes”, it’s possible the files did not even copy.

I’ve never had files physically disappear after a windows update, but it’s possible something is screwed up with the documents library. You should still be able to access the actual documents folder. Maybe open the run box and type in the path to your personal documents folder and see what happens. In my case it would be “c:\users\jm\documents”.