What happens if someone serves out of turn or from the wrong court?

That is a service court error under Law 12. It covers a player who:

• serves or receives out of turn, or
• serves or receives from the wrong service court

When the error is discovered, it is corrected while the shuttle is not in play and the existing score stands. Points already played are not replayed or taken away; the players simply move to the correct positions for the score.