Q: I can't shut down my iPad. I know to press and hold the round "hard" button. Nothing happens.

Try a reset (you need to press two buttons down together)

Hold the Sleep and Home button down until you see the Apple logo.

Instead of the round Home button use the sleep/wake button on the side of the iPad. Press and hold until you see the red Slide to Power off slider.

The Round hard button on the front of the iPad is the Home button. It doesn't turn off the button.

Hold down the thing tab like button on the top of the iPad as seen from the from with the camera on the top part, and the hard round button on the bottom.

http://manuals.info.apple.com/en/ipad_user_guide.pdf

You are most welcome