help me.. what should I do now?
Smart move.
Wow...genius...Easiest thing, just re-install the forum.
Register a new standard user with the username "admin". Then go into your PhpMyAdmin for your forum database and run the following querey:
UPDATE mybb_users SET usergroup = '4' WHERE username = 'admin'
That will make the new account an admin.
You can also set the userID to 1 for the new account (this will make you super admin again)
Go into PhpMyAdmin again and run the following query:
UPDATE mybb_users SET uid = '1' WHERE username = 'admin'
Hope that helps!
Also Make sure your table prefix is mybb_