Here is the problem, you cannot do a back up and restore if you do not remember the code
as this method asks for it for a 'backup'. You may have to go into recovery mode and reset the ipod
Follow these steps to restore your device:
1. Verify that you are using the latest version of iTunes before attempting to update.
2. Connect your device to your computer.
3. Select your iPhone, iPad, or iPod touch when it appears in iTunes under Devices.
4. Select the Summary tab.
5. Select the Restore option.
6. When prompted to back up your settings before restoring, select the
Back Up option. If you have just backed up the device, it is not necessary
to create another.
7. Select the Restore option when iTunes prompts you (as long as you've backed up,
you should not have to worry about restoring your iOS device).
8. When the restore process has completed, the device restarts and displays the Apple
logo while starting up:
After a restore, the iOS device displays the "Connect to iTunes" screen. For updating
to iOS 5 or later, follow the steps in the iOS Setup Assistant. For earlier versions of
iOS, keep your device connected until the "Connect to iTunes" screen goes away or
you see "iPhone is activated."
9. The final step is to restore your device from a previous backup. If you do not have a
backup to restore or have forgotten your restrictions passcode, then restore as New.