Ok, Here's the problem. My friend have a picture over the oil gauge and she couldn't see the oil light on indicating she need to add oil. So she drove the car with low or no oil and her engine now making a loud click click sound. What is wrong with the engine and how can it be fix?

 

That light isnt there to show when you have to add oil, its there to tell you you just messed up the engine. :D
Usually the rod bearings take damage and become spun bearings.

 

id say ya its the rod bearings time for a rebuild or new engine

 

It is trying to tell you to get some oil. I have had a couple of cars in my shop for the test and it's clacking away. Just add some oil it might be just fine.

That is what they always say "it's my wife's/girlfriends car"

 

Yea oil light is a bad thing. This why I don't understand why there is a PICTURE on "her" gauge cluster. Isn't that what picture frames and wallets are for? But anyway, yet if it's clicking and clacking...I'd say spun bearings. Not a good thing, rebuild or new motor. Good luck!