Ok, you take your iPhone > Settings > General > Accessibility > AssistiveTouch > On
A buttom will appear in your screen, it helps users to manage their iDevice if they have an issue. I am for example using it because my Lock/Sleep button doesn't work. Hopefully this helped you. Oh, you might get pissed off of the way you have to do all this to go to the home screen but after some time you'll get used to it.
PS. This is available for only iOS 5 or more.
Feel free to ask me if you still have the issue
