Headphones not detected?

So i got some new headphones and when i plug them in they dont show up in devices or sound? they use a standard 3.5mm jack. http://www.amazon.co.uk/Vox-Amphones-Active-Guitar-Headphones/dp/B009703P7E/ref=sr_1_1?ie=UTF8&qid=1378328687&sr=8-1&keywords=vox+amphones+lead

Headphones wont show up in hardware. within the sound they'll be displayed as the primary output for your computer, which is displayed regardless of if there is or is not any headphones or speakers plugged in.

ah the beauty of onboard sound. go down to the taskbar and right click on the speaker icon, then click playback devices. If there working right (your headphones and onboard) it should be in there.

Yeah i select them but still no sound is played this only happens with the rear IO

Are your motherboard drivers installed?

yeah

downloading the latest audio driver

The connector for the headphones has a switch inside, which is how the soundcard detects if there's something plug in or not, the front connector in my PC broke down a few months ago, I would have to jiggle the plug in and out until the switch moved to make it sound.  

I replaced it with the connector from another case and it's been working fine since then.

Another details was that it would work with pretty much any cheap headphones, but my sennheiser would just not move the switch right, I guess there was a tiny difference in the plug's size.

 

I reinstalled the driver's and its working now thanks so much!

The connector for the headphones has a switch inside, 

Incorrect. The plugging in of a plug into the connector creates a circuit. Obviously the current flow now goes from 0 to a non-zero value. That is how it detects something is connected.