The Apple iPod Nano comes equipped with a safety that allows the owner to create a 4-digit combination to lock the Nano, preventing others from using it. If you cannot remember the code, you will have to use an alternate way. First you will need to connect the Nano to your computer via the iPod USB cable. Start the iTunes application, find your Nano under devices, and select Sync. Once the connection has been made, you can click eject. Now you can safely disconnect your Nano, and it should be unlocked.