Where are my Garageband files?

Is there a Logic folder in Application Support?

GarageBand is sharing the Instruments with Logic and MainStage.

If you cannot find the instruments in the system wide library at the top level of the system drive, check the hidden Library in your Home folder:

The user Library is hidden by default and may still be hidden.

To reveal the hidden User Library:

• Bring the Finder forward by clicking on the Desktop or the Finder icon in the Dock.
• Select your user/home folder (with the house icon in the Finder sidebar)
• With that Finder window as the front window, press the key combination ⌘J to bring up the View options.
• In the View options panel enable ’Show Library Folder’. That will make your user library folder visible in your Home folder, if it is still hidden.
• Open your Home folder, then the Library folder, look for the sub folders mentioned above ~/Library/Application Support/

Check also for the Loops in ~/Library/Audio

The Instruments and lessons should in the following folders

• For the instruments: /Library/Application Support/GarageBand/Instrument Library/
• For the lessons: /Library/Application Support/GarageBand/Learn to Play/

So look into the library folder at the top level of your system drive, then the subfolder "Application Support" and then the subfolder "GarageBand". Are there any files installed?

If you installed GarageBand only for you and not for other users, these files might be in the local Library folder in your Home folder.

~/Library/Application Support/GarageBand/Instrument Library/

~/Library/Application Support/GarageBand/Learn to Play/

/Library/Audio/Apple Loops

/Library/Application Support/Garage Band

That's in the system Library folder at the top level, not your user Library folder.

But think twice before deleting anything. For instance, assets in the Audio folder are used in iMovie and other places.

Are you sure you are looking in the System Library folder (top level) and not your user Library folder (inside your user folder)? Look in both Library folders to be sure.