try pressing the power button and the button on the front of the phone at the same time for several seconds. That is a reset and if it works the "apple" will appear on the screen and then it will reload. If it doesnt work go to the apple store but call ahead and schd a time.
Make a Genius Bar appointment at your closest apple store. They will try to fix it if it dosent work they will replace it, or give you a discount for a new one. Go To make an appointment go to the Apple website go to store locater locate the nearest store and find Genius Bar appointment and the rest is simple
Iphone has great software, what sucks is the hardware(the outside apperance of the phone) it just fails look at "iphone 4 broken" at google images they break so fast even the 3g I like my android samsung galaxy their hardware/software both good