The 20GB iPod is part of the classic iPod series. Occasionally, due to hardware malfunctions, the unit can freeze up and stop responding when you attempt to use the device, preventing you from listening to music on the player. You can usually resolve the issue and unlock the iPod by resetting the unit. If that fails to unlock the 20GB iPod, you can restore the unit to original factory settings. Note that restoring the iPod removes any music currently on the system; always attempt to reset the iPod before restoring it.
Switch the "Hold" button, located on the top left corner of the iPod, off and back on twice, ending on the "Off" position.
Press the top of the control wheel ("Menu") and center "Select" button simultaneously.
Hold the buttons for approximately six to 10 seconds until the "Apple" logo appears on the screen. The iPod will reboot and reset itself.
Connect the iPod to a computer with iTunes installed and an active internet connection, using the USB cable.
Open iTunes by double-clicking on the desktop icon or selecting it from the "Start" menu.
Highlight your iPod in the "Source" panel on the left side of the iTunes program window. Click the "Summary" tab in the center of the iTunes program window. Information about your iPod will appear.
Click the "Restore" button in the "Summary" tab. Do not interrupt the system while iTunes restores the iPod to factory settings. Restoring occurs in two phases. During phase one a progress bar appears on the computer screen; during phase two an Apple logo and second progress bar appears on the iPod screen. Once the iTunes Setup Assistant window appears on the computer screen, the process is complete.
Input a name for your iPod into the "Name" field in the iTunes Setup Assistant window and select your syncing preferences (automatically sync songs, photos and applications or not).
Click "Done" to complete the restore process. If you chose to automatically sync music to your iPod, iTunes will automatically reinstall the songs saved on your computer to your iPod.