Hi Tan,

Here are the required steps

Recovering the Administrator Password

If you lose the Administrator password and cannot access the system, use the following procedure to reset the Administrator password.

NoteDuring this procedure, you will be required to remove and then insert a valid CD or DVD in the disk drive to prove that you have physical access to the system.

Procedure
Step 1Log in to the system with the following username and password:

•Username: pwrecovery
•Password: pwreset

The Welcome to admin password reset window displays.

Step 2Press any key to continue.

Step 3If you have a CD or DVD in the disk drive, remove it now.

Step 4Press any key to continue.
The system tests to ensure that you have removed the CD or DVD from the disk drive.

Step 5Insert a valid CD or DVD into the disk drive.
The system tests to ensure that you have inserted the disk.

Step 6After the system verifies that you have inserted the disk, you get prompted to enter a new Administrator password.
NoteThe system resets the Administrator username to admin. If you want to set up a different Administrator username and password, use the CLI command set password. For more information, see Appendix A, “Command Line Interface.”

Step 7Reenter the new password.

The system checks the new password for strength. If the password does not contain enough different characters, you get prompted to enter a new password.

Step 8After the system verifies the strength of the new password, the password gets reset, and you get prompted to press any key to exit the password reset utility.

Cisco Unified Communications Operating System Administration Guide for Cisco Unity Connection

http://www.cisco.com/en/US/docs/voice_ip_comm/connection/2x/os_administration/guide/2xcucosagpdf.pdf

Hope this helps!

Rob