Original songs not available?

I am trying to download a song from AC/DC and Garth Brooks. Thunderstruck and the Thunder rolls. When I type in AC/DC in the search it gives me some band called ac/db and all the songs are there but not sang by the original band. I also cannot find thunder rolls when I type in Garth Brooks. I can't even find Garth Brooks. Did someone hack itunes and remove orginal songs.