Below you can find the procedure to reset oracle system password in 11G
1) Start the SQL*Plus application
Go to Start -> Programs -> Oracle –> Instance Name -> Application Development -> SQL Plus
2) In the login prompt, in the user-name field enter / as sysdba (including the forward slash) and Click OK.
3) Now you will be logged in as system with full DBA rights.
4) To reset the system password run the following query:
5) Replace the NewPassword with your password and enter.