Starter tested everything’s good but I still can’t start the car

I changed the alternator the battery and the had the starter tested everything’s good but I still can’t start the car. When I go to try and start the car I get no response from nothing and the only thing that pops up on my dash is the check engine light. When I try to turn the key all the way to off position the key gets stuck. What could it be? I tried everything I know.