Board Thread:Help Desk/@comment-68.61.181.238-20130609023403/@comment-24197468-20140227134935

Draco450, if you'd still like to play terraria i might have a solution. I have had it myself as well. If you are using steam and it gives a message "Tarraria is already running" or even gives no message at all, try shutting down your steam client, wait for a minute or so (to make sure its really shut down), and then try to start terraria again. This also forces steam to reboot and starts the game as it should be :)