This usually happens to me when I boot my laptop. The Starting Windows Sound plays, and then I get no sound after that. When I test speakers, it all comes back (Control Panel, Sound, Right-Click Default Device, Test) .
It also occasionally happens out of nowhere, and then I have to test the speakers again.
Beats Audio is disabled, Audio Effects are disabled, Bass and Treble are set to 3, Drivers are apparently up-to-date
I'm using HP DV6-6000 running Windows 7 Professional 64-bit