I did a repair on an Acer laptop, it needed a new power connector so involved stripping the laptop down, after doing this I noticed that the on board mouse / touchpad was not working, I thought I must have not connected it back up correctly, so I stripped the laptop down again and checked and everything was connected ok, looked on the net as to where this connects, and it looked like it was connected ok. I disconnected both ends of the ribbon cable for this and reconnected again, and tested but still no luck. At this point I started to think maybe the ribbon cable was damaged so I removed it totally and tested it with a meter and it appeared to work ok. This is the point you start to panic thinking that maybe something on the mainboard has blown. However after another google on this matter I found it was possible to disable it via some FN keys, so I wondered if I had somehow done this. As luck would have it, I must have “somehow” disabled it.
To fix is very easy, You need to press FN and F7 to (together) to enable the on-board touchpad / mouse.