Balls not to count in the over

a) A ball shall not count as one of the 6 balls of the over unless it is delivered, even though a batsman may be dismissed or some other incident occurs before the ball is delivered.

b) A ball which is delivered by the bowler shall not count as one of the 6 balls of the over

i) if it is called dead, or is to be considered dead, before the striker has had an opportunity to play it. See Law 23 (Dead ball).

ii) if it is a No ball. See Law 24 (No ball).

iii) if it is a Wide. See Law 25 (Wide ball).

iv) if it is called dead in the circumstances of either of Laws 23.3
v) (Umpire calling and signalling Dead ball) or 42.4 (Deliberate attempt to distract striker).

Umpire miscounting

If an umpire miscounts the number of balls, the over as counted by the umpire shall stand.

a) Other than at the end of an innings, a bowler shall finish an over in progress unless he is incapacitated, or he is suspended under any of Laws 17.1 (Practice on the field), 42.7 (Dangerous and unfair bowling - action by the
umpire), 42.9 (Time wasting by the fielding side), or 42.12 (Bowler running on the protected area after delivering the ball).

b) If for any reason, other than the end of an innings, an over is left uncompleted at the start of an interval or interruption of play, it shall be completed on resumption of play.