Chosen Solution
I have a 13” 2015 MacBook pro and the trackpad stopped working but the keyboard is working fine. Could it be the ribbon cable or the trackpad itselt? Tried resetting all kinds of things but did not help.
I would start with the cable as it can be damaged by grit and pressure from the bottom cover and battery MacBook Pro 13" Retina (Early 2015) Trackpad Cable It’s also possible the trackpad damaged. I have had to replace a few as people tend to spray cleaner directly on the case and the cleaner can drip into the gap between the case and the trackpad and works its way into the sensor sandwich damaging it MacBook Pro 13" Retina (Early 2015) Trackpad.
Before replacing the trackpad, make sure to check if it’s the SMC. Use this link.