Disappearing Songs

[Anomaly10]

Does anyone know of any way to recover songs saved for offline playing that disappeared into the ether? I downloaded my playlists for an overseas trip and found a few that I really liked. Unfortunately, they were on Discover Weekly and the second I got an internet connection they vanished. Theoretically the files should still be somewhere on my phone storage, is there any way to see all of the songs made available for offline play?