Why doesn't my key not turn all the way in my car?

I just got this car and it was dropped off by a friend with the car on and running. I drove to the store and came back out to start it and the key wouldn't turn. I fiddled with it a little and it went into accessory mode, but would not start and it would not go back to the off position. I had to leave the car for the night after I unhooked the battery. I just got the car and I need it to run smoothly, thank you, Andy