Check the mute on the video first. Browsers deliberately start video muted — a page that made noise by itself would be intolerable, so autoplay is only allowed silently.
So the commonest cause is not a fault at all. Tap the speaker on the player.
The order to check
1. The player's own mute. The speaker icon on the video.
2. Your device volume, including the silent switch on a phone, which is separate from the volume.
3. Your browser tab. Tabs can be muted individually, and a tab you muted last week stays muted.
4. Headphones you forgot are connected, including Bluetooth in another room. Genuinely the second commonest cause.
5. Reload the page. A stream that lost its audio track does not always recover alone.
Four of those five are at your end, which is not meant unkindly — it is simply where the problem almost always is.
If it is none of those
Is anybody else saying so in the chat? The fastest diagnostic available. A silent show with twenty people not mentioning it is your device.
Try another browser, on the same device. Which browsers does Metzee work in?
Say so in the chat. Hosts cannot hear themselves through your speakers, and a muted microphone is invisible to them while they are talking. Say "no sound" — somebody will tell them.
If the host really is muted
It happens, and the host usually finds out from the chat. Give it a moment; a show does not need to be restarted for it.
Nothing about the auction depends on the audio. The clock runs, bids land, and the item sells whether or not you can hear the commentary. If something is about to close and you still cannot hear, bid on what you can see and ask afterwards. How bidding works
If the video is wrong too
Different problem, different page. The video is green, black or upside down
For sellers
Check your microphone in a rehearsal, not in front of a room. A rehearsal writes nothing real and exists for exactly this. Can I practise before going live for real?
Watch the chat for "no sound" in your first minute. It is the one piece of feedback you cannot get any other way, and a show broadcast silently for ten minutes is ten minutes gone. How to go live
More: what you need to watch a show, the video is green, black or upside down, how fast does my internet need to be.