Go to System > Preferences > Mouse or similar in KDE, and then click on the “Touchpad” tab,check if “Enable mouse clicks with touchpad" is unchecked.You can run from the terminal;
Code:
sudo nano /etc/X11/xorg.conf
type password for sudo and hit enter then find a Synaptics Touchpad Section,it should look like;
Code:
Section “InputDevice”
Identifier “Synaptics Touchpad”
Driver “synaptics”
Option “SendCoreEvents” “true”
Option “Device” “/dev/psaux”
Option “Protocol” “auto-dev”
EndSection
add a line before EndSection (if it's not there)
Code:
Option "MaxTapTime" "20"
If you want to make it more sensitive, increase the value from "20"."0" means disabled.If the section is not there create one with the inputs like above,save the file and reboot.