Everything I write has a soundtrack. I find music that matches the tone of what I'm writing and create a playlist that I'll listen to as I write. It's not something I stick to fanatically, if I'm in the mood to listen to Henry Jackman's score for X-Men: First Class, then I listen to Henry Jackman's score for X-Men: First Class.
But sometimes I need something to remind me why I'm writing what I'm writing. Or I need something to remind me of what tone I'm trying to strike with this story. When I'm writing about the kids on Oasis, I listen to the music of Michael Giacchino and Ramin Djawadi. When I'm writing the adventures of Doctor Phileas Reid, the playlist is almost exclusively Alan Silvestri and Murray Gold.
It helps me. Maybe it'll help you, too.