Are you using the charger that came with it and have that plugged into a known good wall outlet?
First thing to try is to reset your device. Press and hold the Home and Sleep buttons simultaneously ignoring the red slider should one appear until the Apple logo appears. Let go of the buttons and let the device restart. See if that fixes your problem.
If that didn't help you could try using a friends charger and cable to narrow down where the problem might be. Otherwise make an appointment at an Apple store to have the iPad examined.