Did you repair/optimize the attachment table after deleting them? Also, what is the method you used to delete all those attachments?
I didn't do that. Will that remove them from the database?
I first soft-deleted the threads (so that attachments were removed) then I just restored the threads, that way the threads were there but the attachments were gone.
That is not how u remove attachments, all you did was remove them from the post.
Yeah, I think all you did was 'hide' them. I've never had to deal with that problem, but I *think* you just need to go to Admin CP > Attachments > Search and search for all hidden attachments and then delete them. I think if I were to try that, I would back-up my database, put it on my test forum, and try it there first since I have never done it before and would worry about the consequences if I were wrong.