I am using windows 10, Audacity 2.1.1, and an audio-technica ATR2500-USB mic.
Previously its always recorded fine for me. yesterday i plugged in my mic, and double checked the settings which look fine. but when i went to record, it just seems like it isn’t picking up any signal from the mic or anything. although i can hear my voice when i plug my headphones into the jack on the mic.
Check you are choosing the correct recording device in Device Toolbar.
If you plugged the mic in after launching Audacity, do Transport > Rescan Audio Devices from the Audacity menu. Choose the USB codec for the mic as recording device, not the Sound Mapper or Primary Sound Capture Device.