I have in my ipad icloud backup window open and I can't close and I can't do anything I tried to press OK and nothing happen is freezing

Have you tried a soft-reset ? Press and hold both the sleep and home buttons for about 10 to 15 seconds (ignore the red slider if it appears), after which the Apple logo should appear - you won't lose any content, it's the iPad equivalent of a reboot.

View the original article here