In the event that your iPod Touch is frozen and will not respond to any button presses or any attempt to turn it off and on again, then you will need to connect your iPod to your computer and reset, or, in Apple terms, factory restores it using iTunes. This factory restore process will erase all of your settings, data, and media as well as all your emails from your coworkers and clients. After the factory restore, however, you will be able to use one of your previous backups from iCloud or iTunes to put all of these settings and data back onto your iPod Touch.
Download and install the latest version of iTunes if you have not updated this software. Launch iTunes when this is complete.
Plug your iPod Touch into your computer using the USB cable, and click on your iPod's name in the iTunes menu bar.
Click the "Summary" tab, then click "Restore iPod," and click "Restore" again on the alert window that warns you that this process will erase your settings.
Watch the progress of the factory restore by checking the progress bar on iTunes. This process may take more than one hour depending on the speed of your Internet connection. The iOS software image for the iPod Touch is large and will take time to download from Apple servers.
Set up your iPod Touch by sliding the "Set Up iPod" button that appears on your iPod after the restore process completes. During the setup process, you will be asked if you want to apply a backup from iTunes or iCloud.