I screwed up and deleted the launcher for garageband, now I dont know how to start it back up. I have all the files to run it, loops, etc, just not the actual guitar logo launcher.
You are either talking about the icon in the dock or the application itself. If 1, go to your Applications folder and find it. If 2, reinstall from your install DVD (there are multiple install packages on the DVD, usually one per application).