How can I recover lost secure notes in Keychain?
Stupid, silly me.

The left column has a pane for Keychains and a pane for categories.

The keychain pane has 


login
local items
System
System Roots.


The Category pane has


All Items
Passwords
Secure Notes
My Certificates
Keys
Certificates.


These two are in essence multipied together.  That is, ANY of the keychains can have any of the categories.

In my wanderings I was somehow clicked into local items instead of login.  I had not created a local items secure note, so of course secure notes was blank.

Embarrassing as it is, I'm leaving this up for future klutzes.