My c140 won't show anything.

So, I was listening to music. Then turned it off. But later that night went to put music on mine, and I plug it in and when I go to Computer, it doesn’t show Sansa, which is what usually happens. I unplug it and take batteries out, put brand new ones in. Everytime I turn it on, it shows one song, says there’s a low battery, and doesn’t let me do anything. I can’t go to menu, nothing.