Give us some more info on the unlocking. Did you forget the passcode? This should help as well if the tip from iCris should not work for you.
Unlocking iPod
You can unlock iPod in one of two ways:
• Enter the combination code of 4 digit to unlock the iPod. If you enter wrong code combination, the digits onscreen flash red.
• Or Connect iPod to the main computer you use (computer with which iPod synced with), and open iTunes. Now disconnect the iPod from the computer, it will be unlocked.
Unlock ipod without combination code
Now if you forgot you combination code then in this case you have to restore your ipod to factory setting. Important note :-when you reset your ipod, it this will erase all data from your iPod. You need to add your song and data again.