The left earbud of my Bose in-ear headphones doesn't have sound

Either the plus is not completely inserted (most likely) or a wire is loose or the earphones are damaged.

Have you use another headphones insteading of your Sony headphones to have a try? Make sure it is not the problem of headphone, then you may need a headphone jack replacement to replace the old one.
I've also met this situation with my phone. Finally I found the right
Headphone Earphone Audio Jack Flex Cable for Samsung Galaxy S4 i9500 to solve this problem. You can also look for one repair part for your phone, then find a video following to fix. It is easy to make it. Hope it can help.

buy new headphones?. i think a lot better than trying to repair it. it sounds like you are talking about where both earbud wires come together at the molded connector part that splices the wires together. unless you are mechanically inclined and electrically astute, you should just replace the

Could be possibly dirt in Ipad headphone jack (common prob) - put a drop of isopropyl alcohol in Ipad jack - just a drop. You might also check headphones in a computer jack to verify if it is possibly the headphones.

Here is a picture of the final repair

Well, I had the same problem with the right earbud. Luckily I was under warranty with Target, so they told me to contact Bose. I did and they had me send in the headphones (to make sure I waas telling the truth) and about 2 weeks later I got my earbuds back. Their customer service is excellent, so that's what I would reccomend

They should come apart right where the metal meets the plastic, just below the buds themselves - be careful, one set like that I took apart were actually surface-mounted to the housing, there weren't any leads to repair...

whatever the problem is give a call to Bose customer support(800-999-2673) and u can talk with them to get a replacement. If u r in one year warranty they will replace it(even if havnt bought it at bose store)...otherwise they will charge $50 i believe

I have this problem all the time with my JVC earbuds. This may sound a little gross but it will work. I put the ear phone in my mouth and **** on the end of it pretty hard. What I have found is that sweat or even wax will plug the little hole and prevent the sound from coming out.

Well, here's a temporary fix until you guys can get new ones. Pull the plastic stopper about halfway up the phones. Then loop the bottom of the entire headphones through the circle that the plastic stoppers create. When you have a tiny loop, pull the upper stopper down and tighten it. People said that they needed to angle the cable in a certain way, right? Well, this fixed mine for now. Just keep it in that position until you can get a replacement or they come up with a permanent fix.