fish went in rock and never came out
 

i had 2 chromis and they were doing fine together at the begining but one became extreamly aggresive toward the other and forced into the live rock it hasnt been seen since should i try and find its body or just let the life in the rock do its thing

Might have become food for other critters in the tank if it did in fact die, I would not stress about it to much if your tank levels are not out of control.

Happens all the time mate