Earphones problem

Hi everybody! I've got a problem with my Sony earphones. One of them doesn't produce a sound. I've been wondering whether something is wrong with the earphones or a sound card? Could anybody give me advice?

Hi, I'm sure you will have tried this, but in case you haven't, borrow another headset/earphones that you know to be working satisfactorily and plug them into your machine (ckeck for compatibility first) if they don't work either, then it's probably a configuration problem or hardware fault in your computer. Regards paws