You have done well keeping this iPod working this long as this device is now Obsolete. Hopefully you have a backup of all your music. This is one of the older iPods that use an internal Hard Drive. This is usually the part that goes first as they are spinning while in use. More modern devices use Semiconductor Storage like a USB memory stick.
Have you tried holding down the reset keys to completely restart the iPod.
Toggle the Hold switch on and off. (Slide it to Hold, then turn it off again)
Press and hold the Menu and Centre (Select) buttons simultaneously until the Apple logo appears, about 6 to 10 seconds. You may need to repeat this step.
At MacWorldExpo in January 2004, Apple introduced iPod mini, shipping in a smaller form factor and five different colors (silver, gold, blue, pink, green) with a capacity of 4 GB. iPod mini was sold for $249 US
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