The key is stuck in horizontal position

If the lock is stuck in one position, then we need to most likely replace the cylinder. You may be able to loosen it with WD40 but if you tried that and it didn't work then we need to replace it.

https://www.2carpros.com/articles/door-panel-removal

https://youtu.be/XcujVZB7k60

Is the key stuck in the door or are you able to remove it?

I am attaching the info below from the manual on how to replace this so let's run through this and let me know if I am not understanding correctly.

Thanks