If a ball may be lost or out of bounds always play a provisional ball to save time.  Ideally you should play the provisional ball before going forward to search but you may also go back during the 3 minute search period and play a provisional ball while others keep searching for you.  If your original ball is found within the 3 minutes it is still your ball in play and a provisional ball played has to be abandoned.  If after 3 minutes your original ball is not found then continue playing with the provisional ball which is now the ball in play, under penalty.  It is important that someone in the group clocks the time that the player begins a ball search as 3 minutes goes by very quickly!  The search time starts when the player him or herself get to where the original ball is thought to be.