Delstar 1GB MP4 Digital Player

Question

Purchased a Delstar 1GB MP4 Digital Player for our daughter. We loaded some music and it played fine. The next time she tried to use it the screen did not come on and she could not hear any music. She tried to charge it in case the battery was low. She tried both the charger that plugged in to the wall outlet and tried to charge using the USB Cable. The unit is still accessable from the computer and the music is still on the unit.
Do you have any ideas on how to fix this problem?