**SOLVED : SEE BELOW FOR DETAILS**
So I came home today and all the sounds coming out of my speakers is quiet. The volume knob is where it is normally and the sounds is turned up 100% in the Control Panel. I am understandably upset.
My sound card is a CMedia CMI8738 which probably doesn't matter. The speakers are Logitech Z-640s which probably also doesn't matter since it's quiet over earbuds too. Then again, if I knew what mattered, I could fix this freaking thing. Grr.And suddenly it works.
For those curious as to how I fixed it, join the club. I fiddled with the volume slider in the control panel some more, which didn't seem to work because the beep it makes when you adjust the volume was quiet, but then I fired up Winamp (I wanted sound playing while I plugged everything in again) and it worked. Weeeeiiiiiird eh.