I've had alot of trouble lately, after migrating to Elementary OS. The problem is that the touchpad does not work at all. After numerous reinstalls I, somehow, randomly, managed to get it to work, however when I received an information regarding a software update on the Software Center and installed it, when I rebooted, it no longer worked. Since then, I've been aimlessly trying to replicate what happened for it to work the first time, with no luck, unfortunately. I've followed as many threads as I could of people with different OS's and "fixes" for my problem, but none seemed to work.
I recently found this: https://bugzilla.kernel.org/show_bug.cgi?id=81331#c186 Which tells me that my computer used to have this issue in older kernel versions, however it has been fixed on 3.16.0-rc7. My kernel version is 3.19.0-26 so it should have work.