Displaced Bowls.

A bowl or jack on the green that is displaced by a non-toucher rebounding from the bank should be restored to its original position by a player of the opposing side.
Players may not disturb a jack, live bowls, or a jack or bowl in motion until the end is completed and scored (except when a bowl is moved for measuring).
Disturbing The Jack
If a player disturbs the jack, the opposing captain may:
have the bowl or jack restored to its original position;
accept the new position;
declare it dead (if it is a bowl);
have the end replayed in the same direction.