Help, I can hear my students, but they can no longer hear me. My sound and microphone work otherwise

I have had Zoom pro for over 2 yrs and never had a problem with anything. Yesterday I tried to Screenshare a YouTube video, put it on share sound, and lost the ability to have people hear me. My wife could hear the video, but not me! Any ideas here? I have a class of over 30 tomorrow... help!