:eek: I have an unknown 3 handle shower with the middle handle broken off with the screw and part of the pipe that it fits into, in it! How do I fix this now? Thanks!

Remove a handle or take the one that is broken to a place that sells plumbing service parts. They will tell you what faucet you got. Buy the stem, seat, and trim for the replacement of the broken one, but rather see if they have a remodel kit and replace all, or a new one and strip it to rebuild your whole faucet.
Kissler parts company may have your handle online.