Are you logging into the same Amazon account? The mp3s would only be available under the original account you purchased them from.
If you are under the right account, scroll down to on the Your Account page and click on mp3 Downloads under Your Media Library. You'll probably have to log in again. That's where the songs will be stored if you still have access to them.
Once you confirm that you have access, just do a search for Amazon MP3 and click on the cloud player. That's where you'll find all the mp3s you still have access to. You can download the music from there.
Updated On: 3/5/14 at 07:15 PM