How do I replace the cork on a decanter?

You can try a specialty wine shop and see if they know anyone, or a brew shop to see if they might be able to tell you anything.

Are you talking a wine decanter or a spirits decanter? A wine decanter doesn’t need a cork, unless you are storing the wine overnight. A spirits decanter does, but you may be able to have a crystal stopper made that looks better and is more durable than a cork one.

Good luck in your search! : )