Instructions
Turn on your PS3 and log into your local user account.
Select the PlayStation Network icon on the main screen. It is the second-to-last icon on the screen.
Select "Sign In" from the menu. The PSN sign-in screen will appear.
Select the "Forgot your password?" button on the sign-in screen. The password recovery screen will appear.
Enter the email address that you registered the PSN account with.
Choose how to verify your identity. You can either have a new password sent to your email address or answer the security question (the question and answer were both created when your account was registered).
Select "Sign-In" from the PlayStation Network menu. Sign into PSN using your email address and new password.