Ah, geez. He's too young for the beak to have been overgrown, so I'm thinking he's calcium deficient instead. It will be painful for a time, but, like a fingernail that has broken off too short, it will grow back. May take quite a while. In the meantime, you'll have to cut up his food into tiny bites so he doesn't try to use a beak that isn't there. He can just 'tongue' the food into his mouth. And be sure to feed him calcium-rich foods with a tiny pinch of calcium powder sprinkled over the food two or three times a week. He will also need a GOOD UVB light in order for the calcium to be absorbed into the body.