Small segment of screen is unresponsive

Hello, I've had my phone for about a year now, and my phone was dropped with a tiny crack on the screen, but my phone was working perfectly fine. Ever since I downloaded iOS 8 there is a small part of my screen that doesn't respond to touch, it's just below the middle of a phone and it's horizontal across. My screen was replaced yet I'm still having problems, my guess it is that it's the iOS software being corrupt, I spoke to an apple guru and he said he had a problem with his iPad being the same, he told me all I had to do was restore my phone through iTunes, I went through either the procedure and my screen is sti unresponsive.

Any ideas?