You can try using the instructions in the previously answered question or you could perform a PIN recovery using the attached email account. From the moment you forget your PIN, there is a possibility to recover it using the first email that was attached to the phone (a Google account/Gmail). If the phone does have Data Connection enabled, it will send a recovery PIN to your email.
Alternatively, you can perform a factory reset using the Recovery menu by pressing Volume UP + Power button + Home Button. Keep these buttons pressed until the Android logo appears. Select Wipe Data/Factory Reset and you will regain access to your phone.