ACCIDENTALLY STANDING ON A GOLF BALL

If you stand on your own ball as you're searching for it, under Rule 7.4, there's no penalty for such accidental movement by the player (or anyone else) when trying to find and identify it.

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You must replace the ball on its original spot under Rule 14.2, estimating that spot if you're not sure. If you've compressed it into the ground and it isn't lying in sand, place it at the nearest spot with a lie most similar to the original, within one club-length.

However, if you, the player, cause your ball to move before the search has begun (perhaps you stand on it in an area you don't expect it to be and aren't yet looking), you get a penalty stroke.