If you can access the device: Tap Settings -> General -> Reset -> Erase All Content and Settings.
If you can't do that then you need to Restore it as New:
Locked Out, Forgot Lock or Restrictions Passcode, or Need to Restore Your Device: Several Alternative Solutions
Forgotten Restrictions Passcode Help
You will need to restore your device as New to remove a Restrictions passcode. Go through the normal process to restore your device, but when you see the options to restore as New or from a backup, be sure to choose New.
Also, see iTunes- Restoring iOS software.
You can also try using DFU mode:
Placing your device into recovery (DFU) mode:
Follow these steps to place your iOS device into recovery mode. If your iOS device is already in recovery mode, you can proceed immediately to step 6.
1. Disconnect the USB cable from the iPhone, iPad, or iPod touch, but leave the
other end of the cable connected to your computer's USB port.
2. Turn off the device: Press and hold the Sleep/Wake button for a few seconds
until the red slider appears, then slide the slider. Wait for the device to turn off.
* If you cannot turn off the device using the slider, press and hold the
Sleep/Wake and Home buttons at the same time. When the device turns off,
release the Sleep/Wake and Home buttons.
3. While pressing and holding the Home button, reconnect the USB cable to the
device. The device should turn on. Note: If you see the battery charge warning,
let the device charge for at least ten minutes to ensure that the battery has some
charge, and then start with step 2 again.
4. Continue holding the Home button until you see the "Connect to iTunes" screen.
When this screen appears you can release the Home button:
5. If necessary, open iTunes. You should see the following "recovery mode" alert:
6. Use iTunes to restore the device.
If you don't see the "Connect to iTunes" screen, try these steps again. If you see the "Connect to iTunes" screen but the device does not appear in iTunes, see this article and its related links.
If you have a problem getting into recovery mode then try: RecBoot: Easy Way to Put iPhone into Recovery Mode.
Note: When using recovery mode, you can only restore the device. All user content on the device will be erased, but if you had previously synced with iTunes on this computer, you can restore from a previous backup. See this article for more information.
Sounds like the iPod may have iOS 7 and you are running into the aniti-theft feature.
Losing your iPhone feels lousy. Thankfully, Find My iPhone can help you get it back. But if it looks like that’s not going to happen, new security features in iOS 7 make it harder for anyone who’s not you to use or sell your device. Now turning off Find My iPhone or erasing your device requires your Apple ID and password. Find My iPhone can also continue to display a custom message, even after your device is erased. And your Apple ID and password are required before anyone can reactivate it. Which means your iPhone is still your iPhone. No matter where it is.5
try forcing into recovery mode. see http://support.apple.com/kb/HT1808
open itunes on computer - turn device off - plug cable into usb but not device - hold home button and plug in usb cable - release home button after you see the connect to itunes graphic