Earphones appearing as stereo mic

[Tmel14]

I have the Sony noise cancelling earphones and they've always worked fine. I've just tried plugging them in and they suddenly keep appearing as a stereo mic rather than earphones, meaning no sound will play out of them. Any idea how to sort this out?

 

[B. Diddy]

Does that happen with any other headphones? Also, inspect the jack to make sure there isn't any debris in there.