My touch screen is not working but it still displays

So I just found this phone that i got rid of before for an iphone 6, now realizing i dont like my iphone 6 I found it and charged it but my touch screen wont work at all, but display still does. I already took off the top and bottom portions of the phone to reveal the screws. I am just waiting for the phone to die first, but anyone have any ideas how to fix it without taking off the back? And where exactly is the digitizer flex cable inside this phone? My plan was just to unplug everything in it then re plug everything back.