I have the same issue my keyboard and trackpad totally disconnected on my 2015 MacBook Pro 13". It randomly started doing it I haven't dropped it or spilled water etc... I can get my keyboard and trackpad to work if I press down a few times on the laptop with both hands on either side of the trackpad (pretend you're giving it CPR lol), so my only guess is that a ribbon cable is loose somewhere. It's kind of irritating to do that every couple days because it keeps doing it, but at least I can use my keyboard.