IPhone 4s :: Bottom Dock Icons Unresponsive / Screen Works Fine On Apps

I had an authorized seller replace the broken screen on my iPhone 4S, but now the bottom dock of icons is unresponsive. Weird thing is that I can't access the icons on the dock, nor open the lantern / calculator / clock / camera on the icons when I pull up the quick menu, but aside from that, that part of the screen works ... I can use the keyboard completely, you name it, everything except the icons on the dock and the bottom ones on the pull up menu ! Â

The guy who fixed my screen said it must be a software glitch, but I've restarted and restored the phone (from backup and as a new one) and the problem is still there !Â

Any chance he messed up something while changing the screen ?Â

Also, iPhone isn't (and has never been) jailbroken or anything of the sorts