Try setting up Audacity to use “MME” as “host” and “Microphone Array (Realtek R Audio)” as the recording device in the Device Toolbar.
Try recording.
If it records as a flat line, try applying the “Amplify” effect with default settings.
What happens?
With MME as the host and Microphone Array (Realtek R Audio) as the device, it does just record a flat line. I amplified it, and it was still silent, so then I amplified it a bunch of more times, and all I got was static white noise.
With MME as the host
What’s the other one? There’s two different ones.
This amplify thing is a trick because the blue waves only show you about the loudest 25dB out of 96dB. So you can actually have a recording and just not see it. That’s not your problem.
I’ve been known to lose a recording because I set up for Stereo instead of Mono or the other way around. Anything there?
Do you use Skype or Zoom? Is Skype or Zoom still running in the background? Both of those change sound settings without telling you. Close all your apps and clean shut down the computer. Shift+Shutdown > Wait > Start. Not Restart and not normal Shutdown.
That help?
This one is a little out there: Do you get blue waves and just can’t hear them? There are analog recording errors which can cause that.
Koz
My recording is set up with two channels for Stereo, nothing there. I don’t have any other applications open in the background that would conflict, just my internet browser, which isn’t using my microphone. I did a complete shut down of my computer, and started it back up again and tried to record, but that still didn’t fix the issue.
Is this a Desktop? Laptop?
Koz
What’s your microphone and how is it connected? If it has a model number, pretend I want to buy one. There’s something odd about your Windows control panel, but I can’t quite sort it.
Koz
Laptop, Lenovo. Windows 10, I think the version is 20H2. It is just the default microphone on the computer.
See if Audacity works set for mono recording instead of stereo.
Koz
I tried it on a mono recording, still didn’t work. I then decided to close and uninstall Audacity, shut down, power on, then re-install Audacity, which also still didn’t work. It is strange because just a few days ago I was able to successfully record using my microphone with Audacity (Until I updated to the newest version, maybe?)
I can still record device audio from the speakers using Windows WASAPI, that works fine.
Windows detects an input to my microphone, it detects that Audacity is using my microphone, yet nothing records.
Quick note. If you record, say for two minutes, do you get a two minute recording?
Are you trying to do this at one of the two standard sampling rates? 44100 or 48000 (lower left panel)?
yet nothing records.
I’m out.
You have achieved the troubleshooting gold standard. There’s nothing wrong with it, but it doesn’t work.
Audacity acts very strangely if its recording bitstream or service becomes damaged. Freezing or halting cursor and stuttering motion. You don’t have any of those problems. Audacity acts exactly and perfectly normal. I think it is recording the wrong thing, but I don’t see how.
Koz
Google lenovo 20h2 laptop microphone recording settings
https://support.lenovo.com/eg/en/solutions/HT104054
There’s pages of this stuff.
I know this is silly, but is the Audacity recording volume slider turned up?
Koz
Very puzzling 
Perhaps Audacity’s “audio device info” will give some hint.
“Help menu > Diagnostics > Audio Device Info…”
(See: https://manual.audacityteam.org/man/help_menu_diagnostics.html)
Please save the results as a text file and attach the file to your reply (see: https://forum.audacityteam.org/t/how-to-attach-files-to-forum-posts/24026/1)
One more from the ancient writings.
Set it up normally like you would expect it to work. Run the recording slider all the way down, pause, and then run it all the way up. Did it follow you OK or did it jump around, and did it change anything—did recording start working?
Koz
If you are still having issues, do Transport > Rescan Audio Devices, then make sure the Audacity sample rate (lower left-hand corner) is the same as the Windows sample rate, see Direct access to the Control Panel Sound settings, specifically under the Advanced tab.
Koz:
“If you record, say for two minutes, do you get a two minute recording?”
Yes, I do.
“Are you trying to do this at one of the two standard sampling rates? 44100 or 48000 (lower left panel)?”
Yes, my current sampling rate is 44100.
“Is the Audacity recording volume slider turned up?”
Yes, turned up to full.
“Google lenovo 20h2 laptop microphone recording settings”
Thanks for bringing this to my attention, I’ll look more into it to try to figure out if anything’s wrong there.
“Set it up normally like you would expect it to work… Did it follow you OK or did it jump around, and did it change anything?..”
I tried it, nothing happened. The recording was still a thin, flat line.
Steve:
“Audio Device Info/Please save the results as a text file and attach the file to your reply”
Not sure if it’d be of any help, but I added it as an attachment.
Jademan:
I checked, and my Windows Sample rate turned out to be 48000 Hz, while I had mine in Audacity set to 44100. So of course, I turned it up to 48000 Hz, and tried recording. Did it work? Still… nope.
I’m still very confused as to what the problem is, and I’ll try to look more into the standard microphone recording settings for Lenovo 20h2, if that could help.
(Not sure what happened to the attachment I uploaded in the last post… here’s my Audio Device Info)
deviceinfo.txt (4.4 KB)
Go back to that screen and scroll down.
Is Audacity listed as a Desktop app, as shown below.
Yes, Audacity is listed, and is enabled.
“Set it up normally like you would expect it to work… Did it follow you OK or did it jump around, and did it change anything?..”
I tried it, nothing happened. The recording was still a thin, flat line.
I wasn’t clear. There was an ancient problem lost in the mists of time where the graphics on the screen didn’t follow the actual sound setting. When you slowly changed the Audacity recorder slider volume, the graphic wouldn’t follow your cursor. It would jump back and forth as if possessed. Is yours possessed?
You have one of two symptoms. You’re recording the wrong thing or you’re recording the right thing with the recording volume turned all the way down. We remind people frequently that Audacity gets its sound from Windows, not the actual device. So all sorts of demons and gremlins can creep into the process.
And that’s where we are now. Demons and gremlins. You are attracting the attention of the senior officials for the wrong reasons. You just want to make a recording and go home. We would really, really, really want to find out why your system doesn’t work so we can prevent this error in the future.
Your problems fails the Koz Evil Agent Test. If somebody wrote me a big check to intentionally cause this problem, how would I do it? I don’t know. First because you’re on Windows and I’m not, but even past that, I don’t think I could cause what you have.
And that brings us to A Presence. You’re not the only user on your machine. When was the last time you ran that virus check that takes all night? Not that quickie thing that runs behind your apps, but the long, thorough one that takes the machine off-line for a while.
Koz
You may be able to satisfy the requirement of making a simple voice recording and go home…with your phone. This wouldn’t be the first time I’ve recommended stop trying to record on the computer if you’re having problems recording on the computer.
https://forum.audacityteam.org/t/adorable-microphone-for-voice-over-narration/61685/3
Koz