Apple support put me onto doing that when my google calendar decided to stop linking my iphone and my ipad with my windows 7 computer. Works with all versions of iphone and ipad...and should work with a Mac computer.

A "hard reset" is done by holding down the log on button at the bottom of the ipad and the power switch on the top at the same time until the ipad shuts off. That doesn't shut it down complete...it goes dark, then the Apple icon appears on the screen and it reboots. So just hold both buttons down simultaneously till it it goes dark, then do nothing else except wait.

If that doesn't work, call apple support.