Aright here it goes. In league tonight we had a little dispute and no one could come to the correct answer so any help would be appreciated. 

   

   Bob is bowling for team A. He gets up and doesn't look at the pins before he throws. It turns out that he is missing a five pin. The people on the team A noticed that he was missing a pin after he released the ball but before it hit the pins. The players on team B that team A was bowling against never noticed anything was missing since they were not paying attention. So Bob leaves a 7-10 split, and the bowlers on his team say that he was missing the five pin and that he should be able to throw it again. Well they let Bob throw again and he struck on his "replacement" ball. 

 

Hope all that is clear,   basically we are just wondering what the rule actually is, and any help that you guys could give me would be awesome.  

Thanks