This looks to be simply a shaft with a flat to locate a grub screw for an operating knob or handle. Alternatively, it could be for a knob with the corresponding hole and flat for setting the orientation of the switch/dial etc. If it is a bolt it is a case of removing it getting a new bolt and filing/machining the flat in the correct position. I would be very surprised if you could buy one. What is it on/operating?
Hope this helps.