Update:
I brought up Bridge through the finder. Then I closed it through exit.
When I went back into AE I retried using Animation browse pre-sets and tried from file > Browse Bridge, it came up.
I don’t understand why that would make a difference, because after I had closed bridge by using the corner x the link stopped working.
I feel like Alice in Wonderland, I went through the mirror.
However, if this had not happened my next step would have been to unistall [I would have read carefully before using Clean script, maybe yes, maybe no] and reinstalled. For now….back to work
I thank the forum for the patience of a beginner…