My touchbar doesn't work at all.

There is a delicate ribbon cable that connects the touchpad, this is probably where the fault is.

Start with following the first steps in the guide for replacing the screen, to the point where you can see the trackpad ribbon cable. (cable in the image below)

Now when you see this cable, make sure that its connector is properly seated in its position, if it isn't this will most likely solve your problem.

If the above didn't solve your problem, this ribbon may have been damaged during your repair. Look if there are any marks, bends, etc. on the ribbon and if so your problem may be caused by a bad ribbon. If you're unsure, add a picture of the ribbon in your post and someone may look and see if they think its the problem, you can't be sure just from a picture but you can usually get some idea.