How do i repair my wardrobe door?

The hinges work fine, but the doors wont close. on each door there is a piece of shaped metal that is supposed to push inside another component attatched to the central part of the frame of the wardrobe. The metal will push inside but it's not being held there to keep the doors shut. I have no idea what these parts are called and therefore have no idea how to replace them. I can't really afford to buy a new wardrobe.