I did something and my system preferences are gone Now i cant do any tweeks to my system... HELP!

I did something in an update to my computer, and i think i deleted a bunch of files. I had to go to another computer to get Safari back on my computer, and now ive lost all my system preferences. i have no way to update anything on my computer. How can i download this portion of my system preferences so that i can again have control over my computer. any help is greatly appreciated.