Why do some keys fit perfectly into a lock but won't turn? - Quora
What to Do If Your House Key Won't Turn in the Lock
Troubleshooting Key Won't Turn in Ignition: Solutions and Fixes | Key Me
Car Key Won't Turn
Key Won't Turn in Car: How To Find And Fix The Problem | Sure Lock & Key
Key stuck in lock, won't turn or come out. Can't remove mechanism because its riveted into the door frame. Any help is greatly appreciated. : r/AskALocksmith