Dell OptiPlex 755 No Audio Output device and no Sound/Audio in Device Manager

There could be multiple hidden audio devices.

* Press windows key + R
* Enter cmd, click OK
* Type cd\ [press Enter]
* Type set devmgr_show_nonpresent_devices=1 [press Enter]
* Type devmgmt.msc [press Enter]
* Once the Device Manager opens, open Sound and see if you have multiple grey out items. If yes, delete them, then restart the computer and retest

Hi Chris.

Many thanks for taking the time to reply. Your tip ovens up device manager (which I'd previously done but didn't include the results sorry) It does not list any sound devices whatsoever any more, yet did until (I suspect) a windows update possibly removed it. This has happened several times previously yet a download of a soundmax driver has normally cured it, sometimes Windows searches for a driver and installs. This time no amount of drivers will resolve. It could be hardware, as has been very intermittent over the last year, but when I google the issue many other Dell users seem to have encountered it.

Thanks again.

Did you follow SpeedSteps advice? You should disable Windows auto update function so it does not install audio driver on its own.

The other piece of the puzzle is legacy direct play which comes from control panel add features to windows.

Before previous drivers will work in windows 7/8/10 you have to enable legacy features like DOTNET 2.0 3.5  and Directshow.  You must then install DIRECTX JUNE 2010 DRIVERS by downloading the file and extracting into a folder and running DXSETUP.exe.

Directx June 2010 which you download and extract to a FOLDER then run DXsetup.exe as administrator.

http://www.microsoft.com/en-us/download/details.aspx?id=8109

in control panel, all control panel items,  programs and features.

http://msdn.microsoft.com/en-us/library/hh506443%28v=vs.110%29.aspx

Enable dotnet 2.0 3.5

enable legacy directshow.

Install Directx June 2010 Patch.

Downloading Directx june 2010 does not install it.  You have to extract the file into a folder and then run DXSETUP.EXE as administrator.

Legacy audio APIs such as DirectSound, DirectShow, and the waveOutXxx functions enable applications to get and set the volume levels of audio streams.

Windows Media Source Filter. This behavior was maintained to ensure backward compatibility with applications that used the Windows Media Player 6.4. New applications should use the newer versions of QASF, which make the WM ASF Reader filter the default filter for playing ASF files.

Hi speedstep.

Have managed to download directx and, unzip components and run. I then ran R164900 driver ( I already had tried this from Dell) Not made any difference sadly. I seem to have Net framework 4.6.1 installed? Have checked the two boxes you suggested.

Hi speedstep.

Many thanks for taking the time and trouble to spell out a possible resolution.

Unfortunately I'm failing at the first hurdle,  as so far am completely unable to download the directx portion Keeps timing out.of the download.

Will try again later.

Thanks again.

You have to run it in compatibility mode  for vista sp2 and Administrator.

If its too corrupted you may need to re do everything from scratch.

I know this driver works fine with win7 win8 and win10 because I tested it on all 3 versions of windows.

When you check the boxes it has to be online because it gets the files from microsoft online.  If you are not online when its checked it will fail.  You could also have malware.  Easiest way to check this is by F12 booting a Knoppix 7 DVD or a Dell Diagnostics CD or USB Flash Drive.

Description	Supported OS	Download
Dell 32 Bit Diagnostics Utility This package provides Dell 32 Bit Diagnostics Utility for Dimension, Inspirion, Latitude, OptiPlex, Precision, Vostro and XPS models that are running the following Windows Operating Systems: XP and VISTA.More details	Windows Vista 32-bit Windows XP Embedded Windows XP Windows Vista 64-bit Windows XP x64

Hi speedstep.

I've run incompatibility mode and as admin not made any difference sadly. No mater which way I run the driver I get audio drivers do not support this version of software? I also have issues with ie11, I cannot access Hotmail for example unless I run a ie11 window as admin? I've also suspected malware a possible issue, yet have run various tools and rootkits and found nothing! Perhaps my Win 7 install has got corrupted?

Many thanks for all your help, if nothing else I've learned quite a bit!

Hi.

I'm pretty sure I have no malware or rootkits. Have run various tools and cleaners and found nothing whatsoever. The problems seem to coincide with Windows updates. I'm not noticing performance issues, very, very little spam and no unexpected pop ups. Also as many others seem to have encountered this sound issue on Dells, they all cannot have malware/rootkits surely?

Thanks again for your help.

Hi.

Despite the insistence I had malware/rootkits I continued my investigation. I also noticed that Windows updated had stopped working around same time. I managed to get the updates working for MSE but not Windows. I joined the Microsoft WIndows 7 forum but didn't get much useful help. However in another old Microsoft forum I came across a similar issue regarding the updates which suggested registry errors as the cause and the proposed fix was:

Download WindowsUpdateDiagnostic and run then download MicrosoftEasyFix50202 and run.

They found several registry errors and fixed them. I did several re-boots then left PC for awhile. To my delight the Windows update function re-started and the Sound has been restored!

Hope this may help someone with similar Sound issues!

my problem is solved with this post