a couple things to try that more than likely will not fix your problem. do a full restart of the phone. if no success backup the phone a do a full restore. if that doesnt work and you know what you are doing take the glass off the phone and see if the lcd is not completely plugged in. it could have come unplugged by being dropped or bumped. if that doesnt work try to have the lcd replaced. but if it is under warranty take it back!