I start up my game, and there's no sound at all. Everything else works except for the sounds. Any thoughts or ideas? :-/

You need to update your DirectX.

You can download it here:
http://www.microsoft.com/downloads/details.aspx?displaylang=en&FamilyID=2da43d38-db71-4c1b-bc6a-9b6652cd92a3