An iPod Touch can sometimes freeze up if it encounters an application error. Closing the application usually fixes the problem, but occasionally you may have to manually reset the iPod Touch to correct the issue and get the device working properly. You can hard reset the iPod Touch by shutting down the device and turning it back on again or completely reset the iPod Touch from the settings app.
Hard reset - Press the "Sleep/Wake" button on top of the iPod Touch, and simultaneously press the bezel button at the bottom of the screen.
Hold down the buttons for 10 seconds until the screen goes black.
Release the buttons once the Apple logo appears on the screen.
Complete reset - Tap the "Settings" icon on the screen, and tap the "General" tab.
Scroll down to the bottom of the screen and tap the "Reset" tab.
Tap the "Reset All Settings" tab, and then tap the "Reset All Settings" button to confirm the action. If you need to erase your iPod Touch's content as well, tap the "Erase All Content and Settings" option, and then tap "Erase iPod" to confirm the action.