I had to have my 2011 MacBook Pro wiped out and re-installed because of malware. I noticed that my previous package--iMovie, GarageBand, and iPhoto--is not longer installed. I checked online forums and Q&A, and I was able to find iMovie under my purchases in the Apple account. However, GarageBand and iPhoto are not there/ available. I don't understand why one would be associated with my account, and the rest would not. That's odd. I'd like to see what possibility is there to have GarageBand, and iPhoto reinstalled.
Once you do a reinstallation wipe of a Mac all data, including apps (even Apple ones) are deleted. So, unfortunately it seems like you'll have to buy GarageBand (it came with your Mac the first time, right? You didn't buy it separately, did you?). It sounds like you can redownload iMovie, and iPhoto was replaced by Photos (free from Mac App Store).