Hello, I have a HP Pavillion that uses Windows XP.  Recently my computer has
appeared to be playing a sound but I cannot hear anything.  My volume control
icon has disappeared from the taskbar.  I cannot adjust the volume and when I
try to adjust the volume I get an error message saying: "There are no active
mixer devices available. To install mixer devices, go to Control Panel, click
Printers and Other Hardware, and then click Add Hardware."   A day or two ago
I tried to troubleshoot my problem.  After trying to troubleshoot my problem
for a while I got to a point where I noticed there was a yellow exclamation
sign next to a device in the device manager called "Plug and Play
Enumerator".  I then troubleshooted this problem and I was told to try and
reinstall this device by first uninstalling it and then going to Add Hardware
to reinstall it.  I failed at this too because after uninstalling it I could
not figure out how to reinstall it.  So now the device "Plug and Play
Enumerator" is missing.  I do not know if that too has something to do with
my sound problem.  Lastly, when I open Sounds and Audio Devices from the
Control Panel it says that I have No Audio Device.  My sound has been working
fine for the past years until recently.  I do not know if this will help
anyone to figure out my problem but I also have a Realtek HD Audio Manager.  
I would really like to have the sound back on my computer.  Please respond
and help me.  I need major help on this problem.  Thank all of you very much
in in advance.