How do I use both headphone speaker and mic in one port?

[SirDarknight]

My PC has two ports for speaker and mic -

But my headphone has only one cable(plug?) for both speaker and mic. Now my seller won't replace it cause the headphone has no problem and he's accusing me for not checking it before buying.

 

[unksol]

You use an adapter

 

[dudio]

I'm assuming the single jack you have is a 3.5mm.
If so, this would work? If what you have is USB, then they exist as well:

http://www.ebay.com/itm/3-5mm-Stereo-Audio-Y-Splitter-1-Jack-Male-to-2-Female-Headphone-Adapter-Cable-/221413877688?hash=item338d4ba7b8:g:vrcAAOxyaTxTQ2zd

 

[basroil]

Now my seller won't replace it cause the headphone has no problem and he's accusing me for not checking it before buying.

Did the seller claim it was fully compatible with your computer? Did the headphones not list the connection type? If so you can tell him he will refund you or you will file a formal complaint with the BBB/police because that would be fraudulent advertisement at best. If the vendor did not make those claims, he's right and you should have checked the specs.

I always recommend against ebay, so perhaps something like http://www.bhphotovideo.com/c/product/945088-REG/startech_muyhsfmm_headset_adapter_m_m.html is safer to buy from