I'm using wired headphones with a built-in microphone, connected to the 3.5 mm jack on the back of my Lenovo D24-20 monitor. The monitor is connected to my Windows 11 PC over HDMI or DisplayPort. Audio playback through the headphones works, but Windows never detects the microphone.
I checked the Input section under System > Sound and also enabled both "Show Disabled Devices" and "Show Disconnected Devices" in the classic Sound Control Panel, but no microphone appears. There was also no plug-in detection prompt.
Could the monitor's audio jack be output-only? Is there a way to confirm that from the monitor's specifications, or should I test the headset directly with the PC? I also accidentally removed the monitor from my available output devices and would like to know how to make Windows detect it again.
2 Answers
The monitor’s headphone jack is output-only, so it can send audio from the HDMI or DisplayPort connection to headphones but cannot accept the microphone signal from a headset. That’s why Windows has nothing to list as an input device. The Lenovo D24-20 specifications or manual should confirm the jack is for audio output. Plug the headset directly into a PC headset jack, or use a USB headset or USB audio adapter with a microphone input.
A monitor’s audio jack generally appears only as part of the monitor’s HDMI or DisplayPort audio output. Removing the monitor from the output list does not create a microphone device. To restore the display audio, open Settings > System > Sound, scroll to Advanced, and choose All sound devices. Look for the monitor or HDMI/DisplayPort audio device and enable it if it is disabled. You can also open Device Manager, select View > Show hidden devices, and scan for hardware changes. Restarting the graphics driver or reinstalling the graphics driver can help if the monitor audio device is still missing.

That makes sense. I’ll test it directly on the PC and use a USB adapter if the computer has separate headphone and microphone ports.