My Macbook Pro 13" (Latest model) one day decided to stop working completely (got an infinite grey circle at startup). After two days of invstigation, the only solution that worked, was to reinstall the OS by the recovery partition (as my model came without and DVD).
Not only did I loose hundreds of hours of work and editing, but I also lost almost all my archives, which lead me to use a program to recover deleted files.
The problem, is that I didn't get back my Apple loops, nor my Garageband's instruments. I deleted the program and reinstalled it via App Store, but it didn't get my loops nor my instruments.