If someone says çok hastayım, how would you ask what is wrong, would it be hastaysın

Neyin var?

does this just mean what is wrong?

Yes. Did you mean something more specific?

Thanks, no i just like to write my direct translations down in a book

What is an other occassion where you would be expected to reply the same question?

I can´t imagine what you mean. It has a concrete meaning of course, like Neyin var? ´What are you hiding there in your pocket?´.

Or maybe if someone is crying (or laughing) hysterically you should ask her this question.

In a poker game, after auction is over, your opponent will lay down his cards, exposing his hand and ask you "Neyin var?" (what have you got?).

In reply, you will also lay your cards down and show your hand.

The player with better hand wins.