Hi, was the microphone working fine before?
Please make sure the correct microphone is selected. Go to Settings > System > Sound, and under Input, choose the appropriate device. Try speaking and check if the input level bar responds.
Also, check your app permissions. Go to Settings > Privacy & Security > Microphone, and ensure microphone access is enabled for both the system and the app you're using. Additionally, open Device Manager > Audio inputs and outputs and confirm that the microphone is listed there without any warning icons.