After a factory reset, I had lost the touchpad and the screenpad. Installing drivers from Asus website didn't work. Posts from Asus support, Microsoft Answers with all the annoying scripted replies were not helpful. I called Asus support who quickly invited me to return my laptop, which was not what I had hoped for.
I am not sure what the root cause is, but here's a solution that worked like magic for me. I suspect there's a bad OEM driver in the original Windows 10 image that prevents the ASUS drivers to function properly and resist to updates. I don't know which one exactly, but we don't need to.
What we will do is to remove all the OEM drivers from the machine. That is a complete wipe of every non-Microsoft driver. Then, we'll use Windows Update to install all the drivers.
Note: although this is the nuclear option when it comes to drivers, your applications and personal files won't be affected by this.
Save these instructions somewhere.
Make sure applications managing drivers such MyAsus, Intel Driver & Support Assistant, ASUS live update, or any driver manager are disabled or uninstalled. If they prompt to install drivers, decline. Alternatively, you can start with a fresh Windows 10 install.
Download a driver for the Wi-Fi but don't install it. If you lose the network, it will be useful (but it shouldn't happen, the Microsoft driver should be OK).
Open Windows Powershell in administrator mode.
Execute this command:
Get-WindowsDriver -Online | Where-Object {$_.Driver -Match "oem*" } | Foreach-Object { pnputil /delete-driver $_.Driver /uninstall /force }
The machine will be quite busy for some time as the drivers get uninstalled and deleted, screen will flash, beeps will beep. Windows may ask for reboot. Don't reboot until the script ends.
Then reboot.
Run the script a second time for good measure.
Reboot again. The machine is clean.
Now let's fix everything. Don't install any driver from Asus / Intel / NVidia or any other manufacturer website yet.
Go to Settings, Update & Security, Windows Update.
Go to Advanced Options, make sure that "Receive updates for other Microsoft products when you update Windows" is ON. Go back.
Click "Check for Updates". A long list of updates should load. These are drivers.
Install the updates (drivers). Once the updates are installed, reboot.
Go to Windows Update once again and check there's no more drivers to install.
The Touchpad should work now. Maybe you will need to enable it with the function key (F6).
When logging in, a message should appear, inviting to the optimization of Screenpad. Click yes. After a few screen flickers, Screenpad is installed.
Your laptop is all fresh and fully functional.
Optional:
You can now install MyAsus, Intel Driver & Support Assistant or your favorite driver manager to perform the additional updates that Windows Update hasn't seen.
