Try recovery mode
Recovery Mode
Place the iPod in recovery mode using one of these programs:
For PC
RecBoot: Easy Way to Put iPhone into Recovery Mode
or
http://joshuabailey1997.wordpress.com/2010/09/02/recboot-v1-3/
If necessary:
Download QTMLClient.dll & iTunesMobileDevice.dll for RecBoot
and
RecBoot tip
RecBoot may have problems on 64X windows, then try:
Tenorshare ReiBoot – Enter & Exit iPhone, iPad, iPod Recovery Mode with a Single Click
For MAC or PC
The Firmware Umbrella - TinyUmbrella
Installs blootware on PC too
or
If you previously turned on FIndMyiPod on the iPod in Settings>iCloud and wifi is on and connected go to iCloud: Find My iPhone, sign in and go to FIndMyiPhone and use Remote Wipe to erase the contents of your device. If you have been using iCloud to back up, you may be able to restore the most recent backup to reset the passcode after the device has been erased.
You can also wipe the iOS device by installing the FindMyiPhone app on another iOS device and using that app to wipe the device.