How to Do the master reset on the iPhone 3G
If your iPhone has frozen and you're not sure why you're in luck because there is a way to reset it. The first thing you're going to want to do is load up iTunes do a normal reset but don't turn it back on, then plug your iPhone into the connector for your computer but don't actually connect it to the computer yet. Hold down the home button then while holding it plug the connector into the computer. While still holding the home button and have plugged in the connector wait for your iTunes to bring up a message then you can let go of the home button. Then press OK when the message appears then click restore and let it restore then you're finished. This will remove all the data from your iPhone so you will have to re-sync it.