The data on the iPod Touch must be completely erased and then the device restored if you cannot remember your password. By using a service like iTunes, Find my iPhone or recovery mode, you can erase the data and then restore the device.
A passcode can be entered up to six times before the device locks or disables. This applies to the iPod Touch, the iPad and the iPhone.
If the device is synced with iTunes, use the computer on which the device was synced and open iTunes to re-sync the device. If iTunes asks for a passcode to the device, use recovery mode.
To enter recovery mode, turn off the device and disconnect it from any cables. Press and hold the Home button, and while holding it, connect the device to iTunes. If the device does not turn on by itself, turn it on manually. Do not release the Home button. Once prompted to connect to iTunes and enter recovery mode, click OK and release the Home button to begin restoring the device.
If Find My iPhone is enabled, go to the official website and click "All Devices" at the top of the window. Select the appropriate device and click "Erase" to erase the data and the passcode. Complete the process by using the Setup Assistant to restore and backup any data.