Having a precise thread title will help you get more views and possible answers. Your title is too generic.
Also could you specify your problem more?
What hardware are you talking about, what software, what did you do, what is the problem,...?
All I get, is that you have a dead/black line on the bottom of your iPhone screen, which you seemed to get rid of with something doing to a plist file.
Now you can't click on the second row of applications on it.
Does the problem occur on all screens, and how about changing the icons from the second row and placing them in another? Can you access them then?