Yeah, it looks like all the artist and release entities were deleted for some reason (list of creation edits here, I’m pretty sure). I tried looking around to see if I could figure out why, but there doesn’t seem to be any way to filter for arbitrary text in the edit search – it requires the MB ID, which we obviously don’t have any more. Anyone with better knowledge of low-level database queries want to try to find something?
I could be wrong, but I don’t think we have a way of reverting edits, especially deletions, even if we could find them. Your best bet is probably going to be to just recreate everything, but it would be nice if we could figure out why they were deleted before so they don’t just get removed again. I don’t see any reason it should have happened, though, so you’ll probably be fine to go ahead on the redo.