I replaced the keyboard and had to replace the touchpad on my Macbook Pro and now its not working.  Every time I click it will not select what I have clicked on and is basically unresponsive, it even messes up any other mouse I attach.  The arrow still moves around but the actual clicking is not working so I used a USB mouse and avoided the track pad all together.  I looked on line and came up with many people having the same issue.  None of them worked:  Reset SMC, PVRAM, close screen for 60 seconds, and reloading OS, all to no avail.

The actual solution was the adjustment screw under the battery had worked itself down and wouldn’t let the mouse disengage.  When you remove the battery, look toward the bottom of the track pad.  There is a T17 adjustment screw.  Just turn it till you can hear the click of the mouse and everything will work again.