'93s ignition will not stay in RUN position.

My friend's 1993 Grand AM's ignition will not stay in the run position. The car starts, and will run perfect, if the key is held in the RUN position - but it will not stay there. What happened, was his key was stuck, and wouldn't turn all the way to the off position - so I kinda forced it a little bit, and it turned like nothing. He went to start it, and the key would not stay in the run, it just goes right back to off. What causes that?? What sould have to be replaced? I'm hoping nothing too expensive, just the ignition cylinder maybe..

Welcome to AF.

He'll need a new ignition switch and lock cylinder.
Probly not to expensive at your local parts store.