Instructions
Turn on your PS3 and log into the player profile that you wish to restore. The restore process will only affect the profile that is logged in.
Press the PlayStation button on the controller to access the XrossMediaBar.
Navigate to "Settings."
Choose "System Settings" from the "Settings" drop-down list.
Choose "Restore System Settings" and confirm the action in the resulting prompt. Do not turn off the console during this process or you could damage the software.
Log back into the player profile and go to "Settings" again.
Navigate to "Security Settings" and go to "Change password." Notice that the password is now 0000.
Change the password to your desired numeric code.