As I wasn't in the best mental state it's hard to tell what I've done, really. I guess I might have installed the older version and still had the newer version on my pc, but then by installing the newer version again messed with it that way. I do have folders for v22 and v39 in my program files, but they don't seem to contain anything related to bookmarks. In my appdata there's an 'Opera Stable' folder which contains a few files related to bookmarks, however they appear to be on default settings.
I think it's safe to assume at this point they're lost, let this be a lesson to you all! (Don't listen to Larry)