Did you happen to create another admin account? This can be a good idea in just this type of situation .. which I know doesn't help you now if you didn't.
You could try altering the jforum_user_groups table ... make sure the Admin user (ID #2) has an Admin Group (Group #2) in the group_id field. You may want to confirm the Admin UID too (from the jforum_groups table).
But here is a short list of what it should look like. Your Admin acct UID results should be missing the "group ID 2 / user_id 2" entry.