How to access a song that says it isn’t available?

So two years ago I preordered an album on my 6S Plus and the preorder came with a preorder only bonus track. Somehow the album was removed from my music (maybe I deleted it by mistake) and I couldn’t access the song (it said it’s no longer available). I restored to a previous backup and the song was in my library again and I want to know how I can get that song in my library from the old backup to the more recent backup. I no longer can sync it through iTunes because my laptop was destroyed and I have an Apple Music subscription and ICloud Music Library enabled and trying to sync it via ICloud Library didn’t work nor did deleting and redownloading the album. I’m currently using an iPhone X 256GB running iOS 11.1