It's probably the wheel-lock(steering-lock)

When parked at an angle, it can put pressure one direction or another and engage the wheel-lock. This just keeps people from turning the steering wheel when the car isn't running.

Try cranking on the steering wheel left or right while attempting to turn the key. This can, varying by model, take a lot of force to unlock in the position you're in, so don't be nice. It'll feel like you broke something in the steering column and the key will turn. When the engine runs, the steering will get better too as the power-steering kicks in.