There are procedures where Avian Vets can make prosthetic beaks for budgies but I'm sure that would be quite expensive.
Without knowing how much of the beak is remaining and whether or not it too is severely damaged, it is impossible for me to speculate on whether or not the baby will be able to learn to eat on his own.
PLEASE contact an Avian Vet right away and get him in for the proper diagnosis.
I'll be praying for him.
In the meantime, you are going to need to be giving him food and water to sustain him.
With the right owner, willing to devote the necessary time and attention to him, he should still be able to live a happy life.
Please let us know what you find out from the vet.