V-Moda M-100 headphones - sound in only one ear

Rick Slick, probably. Most common here would be a bad headphone jack or a bad speaker (driver) Jiggle and bend the wires at the jack and see if that makes a difference. If it does not, use a multimeter and remove the cover from the speaker part of your headphones. Check the wires between the jack and the speaker for continuity. Let us know what you find and for any issues you can post pictures with your question. Adding images to an existing question

Here is the guide that will show you in principal how to replace the jack How to Replace the Audio Jack