Use this SQL*Plus procedure to unlock and reset user account passwords.

1. Log in as the Oracle Database software owner user.
2. Set the ORACLE_HOME and ORACLE_SID environment variables.
3. Start SQL*Plus and log in as the SYS user, connecting as SYSDBA:

   $ $ORACLE_HOME/bin/sqlplus
   SQL> CONNECT SYS as SYSDBA
   Enter password: sys_password 

4. To unlock an account:

   ALTER USER account ACCOUNT UNLOCK;

5. To reset the password:

   ALTER USER user_name IDENTIFIED BY new_password; 

   Note:

   If you unlock an account but do not reset the password, then the password remains expired. The first time someone connects as that user, they must change the user's password.