Sensors??

[Mooxinator]

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[Big Mike]

If your camera or lens got 'smashed into a door'...it's likely that the lens is out of adjustment and therefore cannot focus properly. The auto focus sensors are in the camera body, as is the camera's image sensor...so it's unlikely that they were damaged...but it's possible.

Can you focus the lens manually?

Do you have another lens that you can try?

 

[Big Mike]

Then it sounds like your 50mm lens is damaged. Take or send it in for repair, not much else you can do.