When a friend goes to a breakout room she finds that her video and microphone are muted. She cannot unmute them. When she returns to mail meeting, her video and microphone are still muted and she cannot unmute them. What can she do?
I don't think she can do anything, but maybe the host can check the settings if he or she lets participants to unmute and start video themselves. Or maybe the host can ask her to unmute and start video.
The same things happened to me when participant uses browser version of zoom. Some participants camera and mic were disabled when joining the breakout room, but in main session they could use their cameras and mic. We asked the participant to restart their browser and then they could use camera and mic.