Usually when a song is stuck in my head I can hear the whole tune, and most but not all of the words. They says that's why it's "stuck" -- if you look up the lyrics and sing it all the way through it becomes unstuck. That works for me. Other people recommend math problems. I would need to revisit math.
Last week I spent two days with only a fraction of a song stuck in my head - just a singer insisting "Get OVER it," followed by a series of descending notes. Google showed me all the songs with "Get Over It" in the title, but that wasn't it, it wasn't the title. Just a part of a line.
But ahhhh, the relief when the neurons finally connected. I finally remembered the song it was from: "Politics in Space" by Kate Miller Heidke. It's 2 minutes and 17 seconds in.