One of the most frequent causes is a locked steering wheel. If you accidentally turn the steering wheel after removing the key, it may lock in place. This makes it impossible to turn the key in the ignition. To fix this, gently wiggle the steering wheel left and right while slowly turning the key. This usually unlocks the steering column and allows the key to turn. https://germanautodoctorsimivalley.com/what-do-i-do-if-my-key-wont-turn-in-the-ignition/