Post a screenshot of what you see.

Here's a screenshot from this morning. (I have redacted personal information.) All emails received prior to yesterday have disappeared.

Try repairing the inbox folder. Right-click the Inbox > Properties > Repair Folder.

thanks. i repaired the folder as you suggested. however, nothing earlier than yesterday appears in the inbox. is the repair only good for future emails, or is it supposed to recover earlier emails that have disappeared from the inbox?

Check that you don't have the Quick Filter Bar set to only show unread mail, and that View/Folders is set to All; press Alt if the Menu Bar with View is hidden.

Check that you don't have the Quick Filter Bar set to only show unread mail, and that View/Folders is set to All; press Alt if the Menu Bar with View is hidden. did all of these; everything was set as you suggested. thanks for the tip about pressing [Alt]!

thanks to all for help and suggestions. regretfully, I'm going back to Outlook; there are just too many loose ends with tbird. Maybe in a couple of years...