I dropped my ipad 2 in it's case and now it won't come on.

I'm afraid that you'll have to make an appointment for the Genius Bar or contact AppleCare using the button in the bottom right of every page, but it will probably mean an Out of Warranty service charge.

You can have a look the pricing here:

Apple - Support - Service Answer Center

Press, and hold, the home and power button for at least 15 seconds or until the Apple logo appears then release both buttons. This may restart your device.