If throwing the ball off a players own backboard is ruled a try, he can retrieve it and start a new dribble.

If throwing the ball off a players own backboard is not ruled a try, he can go retrieve it (similar to ending a dribble and then fumbling) but he cannot start a new dribble.

I guess it also depends what kind of throw against the backboard. If a player is dribbling and two-hand throws it off the backboard, then he has ended his dribble and cannot dribble again if he recovers it. If a player is dribbling and underhand throws it off the backboard, would that be ending his dribble??