in both 2.3.1 and 2.5 beta, when you delete a file from resources, it creates an entry in content_resource_delete. However the file path entry points to a non-existent file. As far as I can tell the old file is simply removed, and not preserved anywhere. If that's what you're goign to do I'd like you to preserve the old file path. Then we could get it from a backup. By changing to a new file path that doesn't exist, you've removed the data we need to do restorations.
I consider this a serious bug. Users expect us to back up their files.