Here is an extract from a member (perhaps King Penguin or Demo) -
Recalibrate the Home button.
1. Open a stock iOS app, such as Contacts
2. Press & hold the sleep/wake button at the top of your device until the red slider control appears.
3. Immediately release the sleep/wake button and press & hold the Home button. Hold until the red slider disappears. Release the Home button.
You should now be on your home screen and your Home button should be recalibrated! Recalibrating your home button this way should work on your iPhone, iPad, and iPod touch.