I'm so smart.
So my laptop wasn't playing any sound. Of course first I check the volume control, not muted, not too low... so I'm like, dammit, why isn't it working... then as I'm thinking about it later, I'm like "Oh yea! There is volume control on the laptop itself!" So lo and behold, I turn it up, and it works. I feel like one those people who are like "My computer won't turn on.... oh it's not plugged in."