I own a 85 190E 2.3. the other day i went to move the car and coul'nt turn the iginition key

Thought it might be dirty or dry tumblers so i sprayed some WD40 into the lock ,didnt work. I also removed the strain from the steering wheel Didnt work. I thoughi I might have a warn key so i tried it in the pass door,glovebox, and trunk it works, Any susgestions would be appreciated thankyou In Advance EARNIE