Speaker icon in Taskbar inactive to left click

I operate Windows 11 Home Ver 23H2 OS Build 22631-4169 with all updates.
Without apparent cause, the speaker icon at the RHS of the taskbar has stopped responding to a left click.
Right click brings up the normal options from "Open Sound Settings" thru the trouble shooter.
The result therefore is I can't turn the sound off. I have to reduce the volume to "0" as a workaround.
I have exhausted all the on line suggestions for fixing this, none of which has worked.
It seemed to happen after a windows update but uninstalling the update had no effect.
I would be grateful for any suggestions beyond the obvious.

Nothing useful in My Computer about the machine involved. I have the later Version of Win11 installed on 4 Notebooks and 2 Desktops, Version 24H2 Build 26100.2605 and no issues with the sound control. The keyboards on the Notebooks have multi-media controls and I have multi-media keyboards attached to the Desktops.

does Win+A launch the quick settings flyout?

Yes on mine.