MS TEAMS sound problem

Teams (via Edge) has almost ceased to work, because nothing I say in a meeting is heard by other members of the Team . Last session I had to use hand signals and hold up notes with Yes / No / Ok on them, to participate! I can hear other participants but they cannot hear me. The Manager says she cannot switch off mute at her end, and I cannot find a way to switch it off on mine. She thinks the error is with my PC, but Windows Settings shows all my sound functions (michraphone etc) are active. If I talk to myself my words and their volume are registered as expected. I think there is a simple answer but have not found it so far.

Things have got worse. The last session was a total disaster for me. Other users could vaguely hear my voice but it was drowned out by really awful sound interference --- it was not the same but reminded me of the feedback howel you get sometimes with audio equipment. As it made it impossible for other users I had to withdraw. I have checked everything I can find on my PC in Settings and Control Panel, but all settings etc appear to be correct.