What is it a movie? If so activate Nero ImageDrive (just open it, it will do the rest), then load the Nero image, you will have a loaded virtual drive now. Play in your player of choice. If it plays correctly, open Nero Express-> Image, project, copy->, you now have 2 ways to do it in Nero. You can 'Copy Entire DVD', using the virtual drive as the source, or you can open the image itself.
If it plays correctly you could also use ImgBurn to burn the image, it handles Nero's .nrg images. Choose 'Write Image file to Disc' and point it to your image.