Server wont start

Im on a mac but every time I do start.command it does this.

Server\ 1.4.6/start.command ; exit;
210 recipes
27 achievements
09:58:09 [INFO] Starting minecraft server version 1.4.6
09:58:09 [INFO] Loading properties
09:58:09 [INFO] Default game type: SURVIVAL
09:58:09 [INFO] Generating keypair
09:58:09 [INFO] Starting Minecraft server on *:25565
09:58:09 [WARNING] **** FAILED TO BIND TO PORT!
09:58:09 [WARNING] The exception was: java.net.BindException: Address already in use
09:58:09 [WARNING] Perhaps a server is already running on that port?
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It has worked in the past but all of the sudden it stopped. Plz help!