Right-click in the white space and ensure Show Disabled Devices is checked
Right-click on the speakers you would like to use (which may have been disabled). If you do not know which to use, try a different speaker than the one with the green check mark
If the device was disabled, click Enable Device first, then right-click on it again
Click Set as default device
Click OK to close the Sound window
Try adjusting the volume as in step number 1. If you hear a dinging noise, the speakers are working properly.