how to enable left click in laptop linux code example

Example 1: Ubuntu 18.04 Mouse right click not working

$ sudo add-apt-repository universe
$ sudo apt install gnome-tweak-tool
$ sudo apt  update
$ gnome-tweaks
//after that go to keyboard and mouse section and click on Area problem solved

Example 2: in ubuntu both mouse pad key working same

//run this command in your terminal window//
gsettings set org.gnome.desktop.peripherals.touchpad click-method areas