Surely many of you know this "trick", but if someone who does not know will save you a fright. May you remain ever iPhone / iPad frozen / blocked and you can not do anything, or use the screen or turn it off or block it, and unresponsive. This may be due to some bug in some application or game, for example.
Well, to "recover" we have only to hold the Home + Sleep button until the iPhone turns off and the apple appears on the screen, then let go of both buttons and ready. The iPhone is normally on and can return to normal use. Keep in mind that estre trick is for iPhone, iPod Touch and iPad.