Those are corrupted or leftover bits and pieces that Windows converts to
files so you can delete them. Most of the time they are just damaged bits of
program files or partial files that are useless, but sometimes you can
recover them, if you know what you're looking for.
For example, if you're looking for photo files and document files, and you
know they were all .jpg and .doc files, you can open the files in Notepad
and see if there's any indication what they are. Doc file will be readable,
but with all the coding visible. You can just rename them with the doc
extension and they might be fine.
jpg files won't be readable, but you might find indications that they are
jpgs. Or you could rename them with the jpg extension, then see if they open
as photos.
Considering that you have about ten thousand files, opening them one at a
time is going to take a lot of time.
BTW, system restore won't do anything for you.