The area outlined by the red line in the picture indicates the part on the screen that is not responsive to touches. Not sure whether it's a hardware or software problem. No physical damage found though.
Tried restoring, it didn't help. Also tried to replace 1.1.1 general.plist into my 1.1.2 general.plist for the touch sensitivity adjustment, when i slide to 16, it really goes less sensitivity, when i slide to 0, it still the same..
But someone from another forum told me that this is surely software problem, but he have no time to teach me how to do it.. Any solution?