There are chipset(source) controls and multimedia/application controls, make sure you check both sources and "save/apply" before exiting. These are interplayable setting, but it may have gooten hosed. If you've done that then check for the latest drivers and if you've recently did this, see if you can go back(restore point). -OR- simply use a restore point when this didn't occur within reason. This is wehere I would start.

happy USA -----Willy Happy