mmm. If its not to old ( the camera) and you paid by creditcard, you might have an insurance that would cover the repair when you send it to nikon....

IMHO, the only option is to take apart the camera and remove the pin from inside.
Check this tutorial (it's for d5100 but I think that d3100 is pretty much the same): http://www.ifixit.com/Teardown/Nikon-D5100-Teardown/5271/1

Thanks, this is my fear, that the body has to come apart. But I am hoping someone knows for sure. Maybe there is some technique I haven't thought of.

donaldejose said:
My wife broke the SD card door on her D3100. The metal pin and spring are still attached the camera. The plastic door is broken off just in front of its hinge mechanism. I ordered a new door but it did not come with any instructions for removing the metal pin to get the old door out and install the new door. Has anyone had any experience with this? I searched the internet for instructions but could find none. Thanks for your suggestions.

I could be wrong, but the body might have to be seperated to get that pin out. It might be best to find the closest Nikon repair center and see if they can help you. Taking the body apart is not a easy task, judging from videos I've seen.

Somebody else might have more info that will help you. I could be totally wrong.

My wife broke the SD card door on her D3100. The metal pin and spring are still attached the camera. The plastic door is broken off just in front of its hinge mechanism. I ordered a new door but it did not come with any instructions for removing the metal pin to get the old door out and install the new door. Has anyone had any experience with this? I searched the internet for instructions but could find none. Thanks for your suggestions.