Charge an iPod without a charger by plugging it into the USB port on a computer that has been powered on. This requires a USB cord with the correct adapter for the iPod, but not a power adapter or wall outlet.
Charging begins automatically after the iPod and computer have been connected with the USB cable. Charging an iPod this way may launch iTunes automatically. Syncing can be avoided by disabling iTunes before connecting the iPod to the computer.
The iPod's battery eventually loses its ability to hold a charge. It may be possible to replace the battery, but replacing the iPod may be more cost-effective if the device is an older, obsolete model.