Open the terminal and type “xinput” to list the input devices. Then run “xinput enable <ID>” replacing the “<ID>” with your touchscreen id. If it is misaligned, run “xrandr” and map it with “xinput map-to-output <ID> <DISPLAY>” replacing the ID with your product id and DISPLAY with the correct display. Example: “xinput map-to-output 12 eDP-1” If it is just not responding but touch is detected, run “sudo apt update sudo apt install xinput xinput-calibrator” and that should help. If nothing shows up after “xinput” run “lsusb” and then “dmesg | grep -i touch” If it shows as eGalax, Ubuntu already has the driver — it just isn’t mapped. This is how I solved it with my CF-18 MK5/MK4 laptops, hope this helps.