Windows 7 No Audio Output Device is isntalled

So..... what you are saying is that, as far as Windows 7 knows, there is no Sound / Audio device present, neither in nor on your computer.
Time to take a look at the system BIOS and see if there is anything in there that has any of the onboard devices disabled or off or whatever the negative not installed setting might be.
 
It would sure be wonderful if I could but unfortunately I can't.
With the method of even entering into the BIOS Setup Utility so varied from Computer to Computer, Laptop to Laptop, Motherboard to Motherboard not to mention the method of navigation once you are inside, the method of changing settings once you find the one you are looking for. I could explain in detail how I would do it on my computer but that would likely be absolutely worthless to you. Heck it wouldn't even work on the other computers in my own home.
You'll need either the Documentation that came with your specific computer or else you'll have to search Google (good luck with those keywords) and see what you can find as it might apply to your specific instance.
All I can say with reasonable certainty is that most if not all have a means of disabling or turning off some if not all of the various integrated hardware devices and I suspect that if Windows doesn't see your device in device manager (even as a problem device) then I suspect that it is either turned off / disabled in the BIOS or is otherwise inoperable as in broken, or failed.
 
Wasn't busy so I did some Google'n for you and found this, which might be a good place to start
To restore the BIOS settings to their default, known good condition, open the BIOS Setup screen as follows:
  1. Turn off the computer and wait five seconds.
  2. Press the Power button to start the computer and repeatedly press the f10 key to enter the BIOS setup Menu.
  3. On the BIOS Setup screen, press the f9 key to select and load the BIOS Setup Defaults. This returns the settings to the original factory conditions.
  4. Press f10 to Save and Exit.
  5. When prompted to Exit Saving Changes?, use the arrow keys to select Yes, then press the enter key to accept the changes.
  6. Restart your computer using the default settings.
Source: http://h10025.www1.hp.com/ewfrf/wc/...product=3740559&tmp_track_link=ot_search#N566
 
Right click it and choose properties, go to the details tab, change to hardware ids and copy and past those lines into your next post
 
IF you right click the problem device.... what does it have to say specifically as to why it's a problem?
 
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