Audio Stopped Working in Middle of Session

My audio stopped in the middle of a session and hasn't worked since---just on my Surface laptop. Everything works fine on my mobile. But I use my laptop for work. People can hear me just fine, but I can't hear them. I've gone through every stage of the troubleshooting, although I couldn't find the file to clean the cache. Nothing seems to work. Has anyone else had this problem and solved it? Thank you so much.