No Audio Device

"No Audio Device" is the message I get when I try to adjust the volume from my "Start" button. I have an old Dell-Optiplex270 running Windows XP with an external speaker unit. I have "RealTech Audio Device" and VLC" Media Player. I read where I need to download "SoundMAX". Help!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!1
 
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