Thanks, Lee.
Luckily, I have fixed this problem. In layout I had to rechoose each field and select the Field Format and select a Value List. It is as thought it had lost the connection between the field and the Value List.
But now that that is fixed, I have another major problem. I am creating new fields which appear in Layout mode, but not when I enter Browser mode in all my existing Layouts. If I create a new Layout, I seem to be able to have a new field appear in Browser mode. But as my Layouts are many and complex, I really do not want to start over and re-create all my Layouts.
I am concerned about a corrupted file. My file could have been open sometime in the past when my System crashed. I have never used "Recovery". I have some backups, but they too might be in the same state. And of course now I have made many changes and additions.
Scott