Change the user password or unlock the user account in sqlplus.

1. Connect as sysdba from the command line:

sqlplus / as sysdba

2. List all users:

select username from dba_users;

3. Check whether the user account is locked:

select * from dba_users where username = 'USERNAME';

4. If locked, use this command to unlock the account:

alter USER USERNAME account unlock;

5. To change the user’s password type the following command:

password USERNAME;