After preparing myself to watch camera video, I dropped my nikon and the dial fell off. Is there a way of fixing this?
Yes. Send it to Nikon Factory Service and let them repair it.
If the dial is broken the only place you can get replacement parts is to send it to Nikon and let them repair it. Nikon no longer sells parts to third party repairers, other than a few external parts. I highly doubt you will be able to obtain a replacement part anywhere other than Nikon factory service.