Have you performed an update / dist-upgrade? If not, do that...
sudo apt update && sudo apt dist-upgrade
If the upgrade includes a kernel upgrade, reboot. If still not working, try this
...(similar to PCNetSpec's earlier post)...
sudo modprobe psmouse proto=imps
If that works it will only work for the current session. To make it permanent, creat a file
sudo pluma /etc/modprobe.d/psmouse.conf
and enter the following in the file you just created
options psmouse proto=imps
Be sure to save the file.Another thing you can try is a boot options edit...
sudo pluma /etc/default/grub
Find the line that reads
and edit it to read
GRUB_CMDLINE_LINUX_DEFAULT="i8042.reset quiet splash"
Save your changes. Then run...
Reboot and see if it works for you.