So it's now doing zilch?
Assuming it's charged (you have a mains charger yes?) ... when you try and power it on, it does absolutely nothing? No flicker of anything on the screen .... no LED's light up anywhere, nothing.
In which case, there is not a huge amount you can try yourself.
Options:
1. Try the reset feature. Trying holding the button down for several seconds rather than just a quick push.
2. Is the battery accessible to you? Try taking it out and checking the contact etc.
3. Try dropping it from maybe three feet or so onto a carpeted surface. Not so high that you'll damage it (it's already bust anyway) but enough to give it a slight jolt. Sounds odd I know, but this has been known to kick start MP3 players.
4. Try taking it back where you bought it and explain the problem. Even without a receipt, many places will help you out anyway.