If a cricket ball disappears beyond an inaccessible area during a hypothetical match, the replacement question is about availability and condition, not an automatic return to a new ball. Earlier play does not restart merely because the ball has gone missing.
When loss can require a replacement
Hypothetical condition A: During play, a used ball travels into an inaccessible area and cannot be recovered. Under MCC Law 4.5, the umpires must replace a ball that cannot be found or recovered, or that they agree is unfit through normal use, with one of comparable wear. They inform the batters and fielding captain. MCC Law 4.5 on the ball describes that requirement.
The replacement selection concerns the ball’s wear, not a reset of earlier play. Keep the existing score record while the umpires resolve the equipment issue.
Why loss is different from asking for a new ball
Hypothetical condition B: The normal ball remains available and usable, but someone asks for a shiny new one because it seems preferable. No separate new-ball entitlement applies in this example. That request does not create the loss-based replacement reason described above. New-ball entitlements at other stages are outside this comparison.
For A, record that the used ball is unavailable. For B, record that the existing ball remains usable. The fact that a replacement is supplied in A does not mean that every replacement must be unused, or that a team can choose a new ball whenever it wants.
What the rule does not change
A lost-ball replacement is an equipment decision, not a new innings, a score correction, or permission to reset the contest. It also should not be described as guaranteeing any particular material or tactical advantage. Exact application can be modified by the playing conditions for a competition, so this explanation states the MCC principle rather than deciding an actual match.