What happens if you turn off automatic compact in Settings, and restart Thunderbird?

doesnt make any difference. I have 2 emails set up in thunderbird. It's only affected one of these and just the inbox in this. Very odd.

Check that there aren't any filters under View/Threads or Quick Filter that e.g. display only unread mail.

these are okay. i think the inbox may have been deleted at the server. Like i said the folders i have still have their messages in them.

Suddenly, my sent boxes on my 8 emails are empty. Each account shows the number of sent emails associated with the address, but none show any individual emails. Am using 138.0b3 (64-bit) Beta. How do I restore my sent emails?

think problem occurred when Thunderbird forced an update the other day. I also had a problem with earthlink not transferring webmail messages to Thunderbird. Earthlink support checked all setting, had me close the computer completely and then restart. This fixed the Earthlink problem but then saw all my inbox emails were gone. No loss in my Sent folder or subfolders.

Another problem with disappearing emails the other day I tried to move a folder in the subfolder tree and it completely disappeared. Checked all other folders to see if it got moved into another folder and cannot find it at all. This all feels like something unstable in the program but cannot seem to figure out how to fix it.