how to get Google Assistant, "OK, Google" back on ?

[bialy]

I seem to have lost Google Assistant. It no longer responds to " Ok, Google ".
Battery settings seems fine.
"Hi Bixby" is working fine.
I recall seeing a voice recognition off message flash on a couple days ago.
I cannot find a simple toggle in any of the Settings to turn Google Assistant back on.
Holding the home key also does not activate the Google Assistant.
Any specific fix here?
Please include detailed step-by-step instructions.
Thanks in advance.