it'd be helpful to be more specific

what brand of headphones?
model?
have you tried googling your issue?
how long have you used them?

Im currently using a steelseries siberia v2 I've googled this problem heaps looked into it and everyone is just saying get new ones
and i've had them for 3 months

Try uninstalling, then reinstalling any drivers you might have for it and restart your PC. If the problem is still happening, maybe they are just borked.

If you've had them for three months, contact SteelSeries RMA. I had an old IceMat Siberia V1 of which a plastic part cracked a month after the guarantee ran out and I couldn't even find my receipt for it. They had me send it to them and a week later I got a brand new headset in the mail. This was many many years ago, though, just after they changed names to SteelSeries; I don't know if they're still that good about their RMA. You should first try rolling the volume controller back and forth quickly a few times, as the wheel sometimes gets stuck internally and stereo headphones often have this weird thing where one of the earcups doesn't work unless you put the wheel in just the right position.

Good luck, hopefully their customer service will live up to its former glory.

if you're really curious as to why it happens, it's probably because of a short in the wiring due to mistreatment/old age. the wires created a path of least resistance for the electricity. not actually fixable, but you could get a new one.
the more you know.

Tested it on another pc yet? if it works fine you have an issue with your pc (likely sound drivers)
If it doesnt work on another pc then RMA them

it's most likely that a cable detached from the volume control, which is the most common problem with headphones with volume control, they're really poorly made.

just send the headphones back to steelseries and let them fix it

Oh I used to have those.

You know the mic I/O switch and volume wheel on your headset?
Basically that thing apparently breaks or screws you over quite easily because of the chip managing your sound or some tech shit breaking for the left side of your headset.

Have you tried tampering with the volume wheel just slightly and perhaps the mic button to see if it works. As in slightly nudge it in one direction or the other.

It worked for a while for me but eventually that stopped working too and I gave up on the headset.

You could always complain to the manufacturer I guess but I just threw them away after that and made it a life lesson to not buy SteelSeries devices again.

(I also had a mouse from them where the scroll wheel stopped working properly as well, quite some time before my headset broke though.)

Try rolling the audio wheel back and forth a little. That worked for me.

This is how I learned to buy headsets without microphone and volume control. I don't own a Siberia myself, but here are two DIY links if you're out of warranty, and feeling really adventurous. I've tried something similar to the overclock project with an old pair of Sennheiser headphones and had great success.

http://www.overclock.net/t/1292403/mod-steelseries-siberia-v2-cord-mod
https://www.youtube.com/watch?v=rUalP7Of7MU

https://dl.dropboxusercontent.com/u/19664301/HeadsetMod001.jpg

8 month old thread

still, it's helpful if someone comes across this thread when buying headphones
edit: i mean the iridescentfuzz guy

Thanks. A few tips for anyone attempting this that I forgot to mention:

If I'm not mistaken, pretty much all cables these days are made of a coil of wire wrapped around some sort of synthetic fibre based thread. Some of the wire may even be coated in a coloured enamel. Usually, you won't even be able to tell the thread is in there. To successfully work with such cabling, you need to do two things. First, take of the outermost insulation(about an inch) being very careful not to cut or damage the two wires inside. Next, twist the coil of wire the opposite direction it's currently going, exposing the fibres. Try and get the individual strands of wire and fibre as separate as possible, then pull all the fibres together and cut them as far as possible. If one or more of the wires is any colour other than copper, that most likely means it has an enamel coating. Get a lighter and briefly flick it on and off, 1-2 times, under the enamel-covered area. Get out some sandpaper, flatten the strands of wire and gently sand them to get the residue off. You'll see them gradually turn from a dusty black to a light copper colour. Test the connection with a multimeter. If there are any copper coloured cables, be sure to test them as well. If they don't seem to conduct you may need to sand them(but not burn them) too.

The regular panel-mount 3.5mm jacks are pretty damn blocky and there was absolutely no way for me to get them to fit inside the earcups of my headset. A good but trickier alternative is to find a really cheap USB sound card, take it apart and cannibalise the output jack. The tricky part is de-soldering it without melting it to a blob. Same applies for soldering it to the speaker leads. Also keep in mind that these are stereo jacks, and if your headset has two separate cables, you'll have to use two jacks, but only solder the 2 of the leads per cable.

Always test your connections at every step. You don't want to solder all your cables, stick the jack in with hot glue and close up your headset to find something isn't working. Find a simple guide on using a multimeter.