Check the selected input
Connect or enable the microphone, then choose Default microphone or the intended input in the test. An unplugged or inactive input may still appear in a device list.
Review permission
Allow microphone access for this site in browser settings. Also check that your operating system permits the browser to use the microphone. An embedded test may need its parent page to allow microphone access.
Look for mute or low input
Check a physical mute switch, headset connection, and the system input level. Speak at normal volume while watching the live meter; a still meter means no signal was detected here.
Close competing apps and retry
Another app, a system setting, or the device can prevent capture. Close meeting apps using the input, select Default microphone, then press Retry microphone. The error alone cannot identify one exact cause.
Compare another app
Try your system sound recorder or meeting app. If it also receives no input, investigate the device or operating system; if it works there, revisit this site's permission and selected input.