Before you can update your preinstalled GarageBand from the AppStore, you need to accept it to your AppleID, if you have not already done so.
Otherwise you will not be able to update using the AppStore.
- Double-click the App Store icon in the dock.
- Enter your Apple ID and password.
- Click Purchases.
- If you haven't previously accepted your bundled iLife applications within the Mac App Store, you should see your iLife applications appear in the Accept portion of the screen. Click Accept.
- You may be asked for your Apple ID and password once again. Your iLife applications now move to the Purchased section. These applications are part of the software that came with your Lion based computer. Your account will not be charged for them. Click Install to complete installation of your applications.
Make sure you are still signed into the AppStore. Then try again to start the download of the missing loops and and instruments by clicking onto a missing loop. Select "Download later". Then look at the "Purchased" tab at the AppStore.
If the download still hangs, check your security settings at the AppStore, see:
Apple ID: Security and your Apple ID
- If your password or your answers to the security questions are too short, your request may not go through, but you will not receive an error message to that fact. In that case sign into "MyAppleID" and reset your security questions.
But that alone may not suffice.
To make the additional content appear you may have to do the full monty and deinstall GarageBand completely, reboot, then reinstall.
When selecting a loop to update, selct to "Update later", and then open the App Store to look for an update.
See Dagon's post here:
Im having the same problem, Given the messsage "the software instrument or apple loop is not currenly installed on you computer. Would you like to install the compleate set ..." and given the option to downlaod now or later, Tried both even after logging into the appstore , but end up with the message "No Updates Available" when i go back to garageband and click on the instruments (eg the ones with the grew download arrow next to them) i get this message "(The Software Instrument or Apple Loop selected is currently being installed.) You have already initiated the installation of additional content for GarageBand via Software Update. For additional information please open the 'Software Update' application." Even after waiting it doesnt make a difference, checked the root folders and the content that is there is there but missing files are not and cant find them anywhere. Also tried ininstalling and reinstalling but it mad no differnece