have you tried everything in this thread? The problem seems to be different for everybody:
If nothing helps try dagon's full monty for a reinstall:
Or a manual download using the Terminal as mteep suggests:
yeah, ive tried everything now, i didnt get a cd so i cant use the first one, and the terminal one just seems to not be able to update it, im really stuck, maybe i should try reinstalling it then using the terminal method, its just that ive reinstalled it about 5 times already, its really starting to get on my nerves
Let me list the exact steps I used, maybe something else is needed, just in case.
1. delete the files under /library/audio/apple loops index/
2. open garageband
3. click on instrument that needs loading, click on option to download later
4. exit garagaband
5. under the apple, pick software update (it opens up the app store)
6. when it says nothing to update, click on command-R
this is when I saw the update show up, the command-R is apparently different than when it loads up and says its looking for updates...go figure, it almost feels like Im running something in windoze!! ha ha
I think deleting that loop index file helps, I just checked and after my download worked that file reappared in that folder, perhaps its blocking you from actually downloading?