Still looking for clues. My wife's son installed Ubuntu 18.04 on a Lenovo Flex 11 laptop, after wiping windows. The computer seemed to work well and I used the touchpad and even the touch screen reliably for a month. Then, I get a notification that an upgrade is available, so I did the upgrade. No apparent change in the screen appearance, it was still Ubuntu 18.04, but now the touchpad would not work reliably. Generally it would not work at all, and sometimes it would work on startup from power-off condition, and then stop working after a minute or two of use. In the intervening month since then, I have chosen to use a wireless trackball, and it always works, so I have full use of the computer. Some degree of portability of the computer is lost though, having to have the trackball with me. First world problems, but I want what I want. I did another prompted update to 18.04.1 and the unreliability of the touchpad continues.
I did an experiment today, when the touchpad decided to work. A screen shot of [xinput list] reveals that the computer/Ubuntu sees the touchpad, as does the long form equipment listing.
screen shot of xinput list
When the touchpad stopped working, the [xinput list] still showed the presence of the touchpad. I powered off the computer, and then restarted a minute later. Now, the touchpad is not working and a new [xinput list] does not show a touchpad. The devices listing from Settings does not show the touchpad, either.
second screen shot of xinput list, minus the touchpad
In reading other postings on this topic, I see that I am not alone, and that no reliable fix seems to be in the offing either.
It would seem that when the computer starts up and gets its instructions on just how to be a computer, those instructions sometimes reveal where the touchpad is, and sometimes that location information is obscured by whatever else the computer is being told by the OS. Or maybe not.
My particulars: Lenovo Flex 11 with Intel Pentium(R) Silver N 5000 cpu @ 1.1ghz x 4, and Gnome 3.28.2, Ubuntu 18.04.1LTS
Is there a fix?