How can I fix my Skyrim sound?

I'd been playing Skyrim for weeks and was almost finished the companion's questline when suddenly the audio just cut out.

It plays in the main menu and while it's loading the game, but just before the save loads, it cuts out.

It plays in menus when the game is paused but not in the main game itself.

I've looked everywhere for a solution, tried changing settings in control panel, all my drivers are up to date and I have directx 10 installed. I also tried the update patch Bethesda released but that didn't help either.