A ball is lost or damaged during the match
Replace it as soon as possible: play does not carry on with only one ball. In competitions the umpire supplies a ball of the same type, new if the balls were changed less than two games ago, and one with similar wear after that.
Never play on with one
If a ball flies over the fence, goes missing or is damaged, another must be put into play as soon as possible. The rules say play does not continue with only one ball available.
Which ball replaces it
In competitions the chair umpire hands out a ball of the same type. If the loss happens within the first two games after a change of balls, the replacement is new. After two games have been completed since the change, it is a used ball of similar wear, so the set of balls stays even.
In social games
Keep a spare of the same kind in your bag. A brand new ball among two worn ones plays very differently, so if you can, swap in one with similar wear.
Questions
What happens if you lose a ball in padel?
It is replaced as soon as possible with a ball of the same type. In competitions it is new if the balls were changed less than two games ago, used otherwise.