IPOD Touch - screen

My ipod, was on earlier, and when I came back to it, screen was black, so I thought it needed to be charged. After plugging it in, normally it would acknowledge the charge on the iPod with the picture of it charging. I wasn't seeing ipod respond to charging, when trying to power it up, it wouldn't come on. Could it be the battery? Or something else.

Thanks,

Tei