What's wrong with my camera? Nikon d5100?

It won't autofocus, and when i use manual focus and take a picture there's a big black square in the middle of everything and you can barely see the picture. What is wrong with it?

It sounds like it's been bashed or dropped and the reflex mechanism that moves the mirror is malfunctioning - it needs service!

It's undeniably broken. Bring it back tot he store you bought it from for servicing.