iPad Unresponsive

I've had my iPad for about 4 months. Usually it works great, but lately I've stopped using it as much (its probably gone about 2 months unused). I realize that's not the best care, but I had to apply to college 🙂 Now that I want to use it again, I can't turn it on. I've tried the hold Home and Wake up/Sleep for ten seconds thing - even thirty seconds - but that hasn't worked either. It's been charging for about 20 minutes now with the 10W power adaptor and is still unresponsive (I've also tried switching out the USB cord to no effect - all the power adaptors and cords I've tried work perfectly with my other Apple products). I'm getting worried that its not even charging. The computer doesn't recognize it either. If y'all have any ideas of what to do other than spending an hour in an Apple Store, that'd be awesome.