Step 1: Right Click on the Desktop and Click ‘Open terminal‘.
You can also open Terminal by pressing Alt+Ctrl+t key on the keyboard.
Step 2: To install System Settings, type the command below in terminal:-
sudo apt install gnome-control-center
if it asks for your permission, press ‘Y’ key on the keyboard.
Step 3: To open the system settings, you can click on show Applications at the bottom left of your ubuntu and Type ‘settings’ in search box.