Hi there thobe47!
Please test the pair with a different audio device and see if the problem goes away first!
Firstly, make sure you are pressing the plug all the way into your audio device jack. Most are designed with two tiers, so only one ear will sound if only one tier of the electrical connection is fully established. Once you've tried that, continue!
Most earbuds are created with very small working parts with equally small electrical connections. If you have lost sound in one side, the most likely cause is a loose connection somewhere.
If it still doesn't work, your options are sort of limited. I would recommend first gently "jimmying" the wire leading to the bad earbud around while it is in your ear and music is playing. If you manage to get the sound to be restored, wrap sticky tape tightly around the wire and the tapered part of the bottom of the earbud in an attempt to maintain the new connection. It is not a permanent fix but might buy you a bit of time with the pair.
If you can't get it to work in that way, your remaining options are pretty much to either open the earbud and attempt to reestablish the connection (difficult, small parts, and could damage the earbuds if you don't know what you are doing), or to buy a new pair. You can get some pretty nice earbuds for under $5 at most megastores, and anybody who could fix them and would charge you will charge you much more.
If you must try to open the earbud (I don't recommend it!), I have a generic set of steps here. I take no responsibility for damage of your earbuds or devices that may follow!
Gently peel back the gelly cover of the earbud, starting under the top seam and pulling it off.
Unscrew or "pop off" the portion of the earbud that has the small grating. There may be an inner retaining system involving more plastic rings. Just keep these safe and remember the order in which you took them apart.
You will now probably be seeing the speaker of the earbud, looking like what you might see on an uncovered subwoofer speaker (just much smaller!)
Being careful to not touch the flat portion of this disk and avoiding anything magnetic (including your laptop / desktop), see if you can pinch it by the sides and gently pull it out of the casing -- probably less than a quarter centimeter. If you can, look for any severed connections between the solder points on the bottom of the speaker and the wires coming from the bottom of the bud. Soldering these would be extremely difficult, but you can attempt to fix them with small pieces of tape.
Nestle the speaker back into the housing, replace any retaining disks in the correct order, screw/pop the outer clip back on, and slide the gelly back into place.
Hope this helps!
JVC Gumy Ear Bud...
on Nov 28, 2016