ORA-28000 Error: ORA-28000: the account is locked
Cause: The user has entered wrong password consequently for maximum number of times specified by the user’s profile parameter FAILED_LOGIN_ATTEMPTS, or the database administrator has locked the account.
Action: Wait for PASSWORD_LOCK_TIME or contact the database administrator
To unlock an user manually:
alter user <username> account unlock;
to change his password:
alter user <username> identified by new_password;