I saw that answer and I have to admit I did lol. Such a simple fix..
Problem obviously if they are comfort fit headphones, ergonomically designed to fit different ears. If its really bothering you cut the wire and solder it back again in reverse. Although I wouldn't recommend it if the headphones cost anything much.
Alternatively, IDK what sound card you have, but there might well be some software that came with it? If so check for an option to reverse stereo, it's a fairly basic option.