ubuntu 12.04 admin password account disabled

i have ubuntu lts 12.04
i wanted to make a new administrator.....i created a new user..made it admin and made the earlier user standard....but accidentally the new admin user password says "account disabled"... now i can only log in with earlier user(standard) and not with admin......
i tried recovery mode
in the recovery mode it asks for "root password for maintenance"...which i don't know....

also if i try to solve using terminal in earlier user it says "user not in sudoers file.This incident will be reported"...........
how can i access the admin account or create a new one......help