This literally just happened to me, my iPod was working fine and within 15 minutes of using it and when I went to check it I find out it wasn't responding to the lock key or home buttons. It wouldn't connect to a computer/console and subsequently would charge.
TO FIX THIS:
Hold both the lock and home keys consecutively for AROUND 3-5 seconds
Let go of ONLY the home key.
You should see the apple logo and then it will start up normally.