No Sound in DirectX Games

Any game/program that primarily uses DirectX now has no sound. I've tested numerous flash games and every single one has sound. I tested many games on my system like Garry's Mod, BeamNG, Just Cause 3, GTA V, and Half Life 2. Every one of them had no sound. Any help?

PC Specs
Make: Alienware 17
Processor: Intel Core i7 4720HQ CPU 2.60 GHz
GPU: Nvidia Geforce GTX 970M
RAM: 8 GB
OS: Windows 8.1 (x64)

I really don't want to have to factory reset my computer, because when I did it last I had...

No Sound in DirectX Games