How can I get my dryer to close?

How can I get my dryer to close? It was working just fine this morning, now every time I close it it just pops back open. There's this little lever thing hanging from the top left corner that I never noticed before, but now when i close the door it makes a popping sound and opens back up. I don't know if it's the little lever thing or the latch to the door that's on the top middle part of the dryer door.