Currently Being ModeratedNov 5, 2013 11:26 AM (in response to legocjman)
Is GarageBand installed in the Applications folder and simply called GarageBand? If not, move it back.
Try the solutions discussed in this thread: Themanual install discussed by mteep, reloading the AppSTore.
However, I am not sure, if these still will work wizth Mavericks. This may have changed, after GarageBAnd 10 was introduced at the AppStore.