the battery may have finally died - this is one of those planned obsoletion things about the ipod shuffle - it is sort of disposable...once the battery in these goes - you need to get a whole new unit to play songs as I don't think they can be replaced!
I am just waiting for mine to die soon.
One good thing though - the new ones are cheaper and clip onto your clothes - better for getting around with and you don't need to have a dedicated computer with your itunes on it to recharge.