Replaced broken screen and now touch is non responsive. Help!

The first thing you need to do is to eliminate replacement parts as the issue. Try installing the original screen to see if the issues persist. If everything works fine (or at least, as they did before the repair), then you may have either a defective replacement part or it was damaged during the repair.

If the original screen also shows the same symptoms, then you may have damaged something. Closely inspect the flexes, connectors and surrounding area on the logic board to see if there is any physical damage such as tears (even tiny ones!), broken or bent pins in the connectors or any signs of dislodged parts on the logic board. Use magnification if necessary.