Door lock problem

[makler]

My door lock is not working with the key. I’ve read some older posts but none of them seem to have a resolution to the problem posted. This is not an electronic problem, it’s mechanical. When I turn the key, there is no resistance, it just spins a quarter turn to the left or right. I called a locksmith to unlock the door and it was unlocked by pulling the inside door handle. A body shop guy said it sounds like the rod that connects the tumbler to the rest of the door lock fell off. I looked at my Bentley guide an noticed there really isn’t any kind of rod other than the one that runs from the inside door handle to the lock. I’m wondering if this could be something as simple and a part needing to be put back into place, or if I’m going to have to replace the whole damn thing? Any help is appreciated!