ORA-28000 error - Account is locked due to expiration

ORACLE ERROR:ORA-28000: the account is locked

From your command prompt, type 

sqlplus "/ as sysdba"
Once logged in as SYSDBA, you need to unlock the SCOTT account
SQL> alter user system account unlock;
SQL> grant connect, resource to system;

Or you may do as below :

If the account is locked due to password expiration, you will probably need to reset (not necessarily change) the password:

ALTER USER user_name IDENTIFIED BY password ACCOUNT UNLOCK;

Hope this helps....