No audio output device

Hello!
I have a common problem: my Windows 10 has No Audio Output Device.
System configuration:

• Lenovo Legion Y520-15IKBN (laptop)
• Windows 10 Pro, version 1909, build 18363.535;
• Current updates;

Device manager shows these audio devices:

• High Definition Audio Device (driver version 10.0.18362.356)
• Intel Display Audio (10.27.0.6)
• ASUS Xonar U3 (10.0.8.2164)

i.e. the problem persists even with an external (USB) audio device, recognized by the system.

I performed a sanity check on this issue. Sound works when I boot into Ubuntu live. Therefore, it is not a hardware problem, and is indeed a Windows problem.

Solutions that have not worked so far:

1. Audio troubleshooter (issues found: check audio device, nothing else)
2. Rolling back drivers
3. Uninstalling audio devices
4. Uninstalling any audio-related devices, incl. the likes of bluetooth speakers
5. Updating audio drivers (from both built-in drivers and from manufacturer's site)
6. Installing a generic audio device (installing a generic USB audio device does not succeed, and installing a generic Realtek device resulted in a BSOD)

Do you have any ideas for fixing this?

Thanks for a quick response!
I cannot remember the exact situation and a course of action that led to the current state. I was installing some driver updates, namely, Intel Rapid Storage Technology Driver, Intel chipset driver and a BIOS update, everything from the Lenovo website. I am not sure which one to blame, but one of these flipped a switch in BIOS and set my hard drives to RAID (my laptop has two drives, and they are not supposed to be made into RAID). This led to some confusion, as I could not boot Windows, and I have fidgeted a bit with drive letters and boot options from the recovery command prompt. Eventually, I noticed the incorrect BIOS setting, and with that my machine booted normally.
After that, I honestly do not remember, whether audio disappeared with those updates, or after later Windows update (I think, it was November feature update).
Now, Lenovo System Update tool is not working for me, throwing "An error occurred while downloading packages". It also keeps a weird logfile:

Code:

[Lenovo System Update build: 2019-08-01 5.07.0088]	01-Jan-20 18:49:29 (note the timestamp)
. . .
Info	2020-01-01 , 06:49:34 (a different timestamp!)
	at Tvsu.Engine.Process.HelpCenterQuestProcess.LaunchEgather()
	Message: Launching Egather

Info	2020-01-01 , 06:49:34
	at Tvsu.Egather.EgatherManager.GetEgatherParser(String type)
	Message: Running egather complete.....

Info	2020-01-01 , 06:49:34
	at Tvsu.Engine.Process.HelpCenterQuestProcess.LaunchHelpCenterProcess()
	Message: Launching HelpCenter

Severe	2020-01-01 , 06:49:34
	at Tvsu.Engine.Process.HelpCenterQuestProcess.LaunchHelpCenterProcess()
	Message: An error ocurred while contacting the help center
	Exception:
		Message: Index and length must refer to a location within the string.
Parameter name: length
		Type: System.ArgumentOutOfRangeException

Info	2020-01-01 , 06:49:34
	at Tvsukernel.CustomControls.Step.<>c__DisplayClass7.<set_Image>b__6()
	Message: Setting DONE status.

Info	2020-01-01 , 06:49:34
	at Tvsukernel.CustomControls.Step.<>c__DisplayClass7.<set_Image>b__6()
	Message: Setting PROCESSING status.

Info	2020-01-01 , 06:49:34
	at Tvsu.Engine.Task.Task.Start()
	Message: Executing the PostProcess HelpCenterQuestProcess

Severe	2020-01-01 , 06:49:34
	at Tvsu.Engine.Task.Task.StartExecution()
	Message: An error occurred while the task: ApplicableUpdatesTask executed the process: HelpCenterQuestProcessthe message from exception isIndex and length must refer to a location within the string.
Parameter name: length
	Exception:
		Message: Index and length must refer to a location within the string.
Parameter name: length
		Type: Tvt.FileDownloader.DownloadException

Info	2020-01-01 , 06:49:34
	at Tvsukernel.CustomControls.Step.<>c__DisplayClass7.<set_Image>b__6()
	Message: Setting FAILED status.

Info	2020-01-01 , 06:49:34
	at Tvsukernel.Logic.ProgressThreadEService.HandleResultStatus(Exception e)
	Message: Error while downloading packages.
	Exception:
		Message: Index and length must refer to a location within the string.
Parameter name: length
		Type: Tvt.FileDownloader.DownloadException

Info	2020-01-01 , 06:49:34
	at Tvsukernel.Logic.GUIController.ShowErrorMessage(Exception e)
	Message: Error while downloading packages.
	Exception:
		Message: Index and length must refer to a location within the string.
Parameter name: length
		Type: Tvt.FileDownloader.DownloadException

Info	2020-01-01 , 06:49:34
	at Tvsukernel.Dialogs.Messages.ShowStaticMessage(String message, String title, MessageType t, Boolean check)
	Message: Showing ERROR Message: < An error occurred while downloading packages. >

Info	2020-01-01 , 06:49:36
	at Tvsu.Egather.EgatherExecutor.ExecuteEgather(String fileOutput, String args)
	Message: RC eGatherer: 0

There are no strange beeps on the startup

Results from aforementioned thread are not directly applicable, as my device manager does not show any unrecognized / unknown driver devices. I have downloaded Speccy, and on the "Summary" page it only displays "Intel Display Audio" under the "Audio" tab. Does this mean that IDA is somehow set to be the default device? Because, when I view the "Audio" page, it lists two audio cards, IDA and a "High Definition Audio Device". It also indicates that my speakers are configured in stereo mode.

Thanks for new ideas!
Regarding that Youtube link: this solution does not work, as mentioned in the 1st post.
I do not have any 3rd party security software.
No startup sounds of any kind.
chdksk and sfc have not found any errors
Clean boot into new account didn't change anything.

dalchina said:

You could try an in-place upgrade repair install which keeps all progs and data - you'll need a 1909 iso file - use the MS media creation tool.

That will reset services to default, provide a new set of drivers etc.

Thank you! This is what finally did it.
For those who may end up here through googling the same issue: this is how you perform a repair install.