Some time ago, my iPhone crashed, freeze and I couldn’t make it reboot. Besides, in the iPhone isn’t easy to remove the battery.
After searching for a solution I found that there is a way to reboot the iPhone, just using a combination. To do it, we need to press two buttons at the same time. One is the awake / sleep button, that can be found on the top left corner and the other one is the front button. After pressing these buttons the iPhone shuts down and then shows the apple.
I hope we don’t have to use the trick many times, but keep it in mind just for the cause it happen.
If you need other troubleshooting for the iPhone visit http://ipod.about.com/cs/qt.htm