The rules of cricket
Law 20 (Lost ball)
1. Fielder to call Lost ball
If a ball in play cannot be found or recovered, any fielder may call Lost ball. The ball shall then become dead. See Law 23.1 (Ball is dead). Law 18.12(a) (Batsman returning to wicket he has left) shall apply as from the instant of the call.
2. Ball to be replaced
The umpires shall replace the ball with one which has had wear comparable with that which the previous ball had received before it was lost or became irrecoverable. See Law 5.5 (Ball lost or becoming unfit for play).
3. Runs scored
(a) The penalty for a No ball or a Wide, if applicable, shall stand, together with any penalties under either of Laws 18.5(b) (Deliberate short runs) or 42 (Fair and unfair play) that are applicable before the call of Lost ball.
(b) The batting side shall additionally be awarded
either (i) the runs completed by the batsmen, together with the run in progress if they have crossed at the instant of the call,
or (ii) 6 runs,
whichever is the greater.
4. How scored
If there is a one run penalty for a No ball or for a Wide, it shall be scored as a No ball extra or as a Wide as appropriate. See Laws 24.13 (Runs resulting from a No ball – how scored) and 25.6 (Runs resulting from a Wide – how scored). If any other penalties have been awarded to either side, they shall be scored as penalty extras. See Law 42.17 (Penalty runs).
Runs to the batting side in 3(b) above shall be credited to the striker if the ball has been struck by the bat, but otherwise to the total of Byes, Leg byes, No balls or Wides as the case may be.