Step-1 Need to find user details by using below query
SQL> select username, account_status from dba_users where username='BOB';
USERNAME ACCOUNT_STATUS
------------------------------ --------------------------------
BOB EXPIRED
Step-2 Get users password by using below query.
SQL>SELECT 'ALTER USER '|| name ||' IDENTIFIED BY VALUES '''|| spare4 ||';'|| password ||''';' FROM sys.user$ WHERE name='BOB';
ALTER USER BOB IDENTIFIED BY VALUES 'S:9BDD17811E21EFEDFB1403AAB1DD86AB481E;T:602E36430C0D8DF7E1E453;2F9933095143F432';
Step -3 Run Above alter query
SQL> ALTER USER BOB IDENTIFIED BY VALUES 'S:9BDD17811E21EFEDFB1403AAB1DD86AB481E;T:602E36430C0D8DF7E1E453;2F9933095143F432';
User altered.
Step-4 :Check users account status
SQL> select username, account_status from dba_users where username='BOB';
USERNAME ACCOUNT_STATUS
------------------------------ --------------------------------
BOB OPEN