I messed up a little on the forums when I was granting access to users. I also changed my own access a little and somehow the controls allowed me to remove myself from the Administrators role.
Surprisingly, there wasn't a check in place to see if there were any other Administrators, meaning the board was without an admin.
So I took a look around the database for a way to add myself back in.
Luckily, the tables were described in the documentation wiki pages.
Firstly, get the Administrator group ID from mybb_usergroups. For me, the group ID was "4".
Now you'll have to update your own primary user ID to match the admin group ID. You can find that in the mybb_users table.
Armed with the correct information, the query you should end up with is:
UPDATE mybb_users SET usergroup = 4 WHERE uid = 1
Where user ID "1" is the admin account.
PS. The table names shown are assuming that your database table prefix is "mybb_".