I had an interesting Thunderbird problem where certain emails seemed to disappear from my Inbox, but searching for them still produced results. That made me wonder whether the messages were actually deleted or simply being hidden or moved.

I found a recent Mozilla support discussion with a very similar situation. The user could locate messages with Thunderbird's quick filter even though they weren't appearing normally in the Inbox, and folder repair was eventually suggested.

It seems filters are worth checking before assuming there is serious corruption. Thunderbird's Message Filters can automatically move, delete, or otherwise process incoming messages, and an old rule can continue running without being obvious.

If someone is looking for Fix Thunderbird Inbox Emails Disappeared, I'd suggest checking Message Filters, Trash/Junk, folder view settings, and then trying Repair Folder.

My bigger question is what to do before experimenting with the profile. Has anyone tried the DRS Softech Thunderbird Backup Tool to create a backup first? Being able to preview the mailbox and selectively export emails sounds useful when you're worried that troubleshooting could make the situation worse.