If you launched Stykz and you don't see a Stage window show up, or the Welcome Screen doesn't appear, it might be because another instance of Stykz is currently running (maybe due to a freeze or crash).
To check to see if this is the case, you can right click on the Task Bar and choose "Start Task Manager" from the popup menu:
When the Task Manager displays, click on the Processes tab:
Click on the Image Name column to sort the processes, and then look for one (or more) marked Stykz.exe (could also be shown as Stykz .exe *32) (1). Select it, and click End Process (2). You'll get a confirmation dialog box; click the End Process button and the entry will be removed from the Processes list.
Continue to delete these instances of Stykz until there aren't any more in the process list. Close the Task Manager and then launch Stykz again; it should launch normally and then you should be good to go!