If you have forgotten the SYSTEM / SYS password of Oracle Database, it is possible to set it from sqlplus command prompt window.
Steps:
1. Login to the Windows machine as an Administrator where the database is installed.
2. Start > Programs > Oracle – Instance Home Name -> Application Development > SQL Plus
3. Type “/as sysdba” (without the quotes) and press Enter. SQL Prompt appears.
4. ALTER USER SYS IDENTIFIED BY ADMIN123; (replace ADMIN123 with your password) and press enter. You should see “user Altered” message.
