Your phone uses a single connector on the display itself, unlike other phones such as the iPhone where there are separate flex cables for the display and the digitizer. So all the signals for the touch screen run through that one connector, shown here.
[image|3195109]
Of course, that connector plugs into the daughter card, not the motherboard, so there are more connectors and cables in the path; you have to get those signals from one to the other after they come in from the display. There are two cables and there's no sure way to tell which one those signals travel on, but I'd suggest starting with the one right next to the display connector here.
[image|3195111]
And here's the other end of that cable.
[image|3195112]
I suspect the other cable is probably not what you're looking for, but have no way to be sure, so you might end up having to replace that one as well. Here's the other one.
[image|3195115]
Assuming you can't find anything wrong with the connectors, I'd suggest you start replacing parts. The daughter card is the first one in the path; that receives the display signals and passes them along, so any damage internally or to any of the connectors could cause it to fail.
In addition, those two interconnect cables, labeled as left and right in the guide, are likewise susceptible to damage and could be the source of the problem, so replacing them is another possible fix.
So I'd suggest replacing those three parts and seeing if that gets your touch screen working again. Of course, it's always possible you've got a defective replacement screen, so if possible you should try the original screen and see if the touch still works with it; if so, you should consider that your new screen might be bad.