Did you activate the Quick Filter for your Inbox?

How do you activate the Quick Filter for Inbox? In the upper right is quick filter tab. I click that on and there is a search bar that appears. what does that have to do with all the previous emails from months ago disappearing from the inbox?

Are all the emails from inbox on a Thunderbird or Mozilla server?

inbox shows I have 7 messages, I used to have over 2000.....where did the rest of them go??

You didn't tell what happened before your messages "disappeared". First: do you use a POP or an IMAP account? When you use IMAP your messages are stored on the server of your email provider which has nothing to do with Thunderbird or Mozilla. With the IMAP protocol Thunderbird (or any other email client) reflects the situation on the sever like in a mirror, that means Thunderbird synchronises with the server.

With the POP protocol messages are stored locally on Thunderbird. When you download messages from the server Inbox they will be stored in your Thunderbird profile. According to your server settings in Thunderbird downloaded messages grosso modo may stay on the server or may be deleted from the sever immediately or after some time.

The fact that your Inbox shows only 7 messages may be caused by an erroneous choice of message view. That's why I asked you whether you have activated the Quick Filter and now want to explain its use by an exemple: in my image I show an account Inbox which contains 122 messages. Now I activate the Quick Filter button "Show only unread messages" and the thread pane displays only 3 messages, because these are the unread messages of a total of 122 messages in Inbox.

I would like that you show a similar screen shot, so we can see whether you are a victim of this frequent "view" choice error.

thank you for your help Mapenzi the night before the messages disappeared, I had shut down the computer from the start button-lower left corner. started it the next morning but there was a message saying it was repairing and then click on restart. When I started Thunderbird, that's when I discovered all previous emails were missing.

I use a POP account None of the quick filter buttons are activated

posting 3 screen shots

Thanks for your screen shots. Unfortunately your pop.att.yahoo.com account is empty except for a couple of messages in the Inbox. Did you verify the Yahoo webmail whether messages are still on the POP server? Probably no, since in the Server settings you unchecked to leave messages on server. I have no idea where your messages have gone and how to retrieve them, unless you have a backup of your Thunderbird profile.

Here is another screen shot if you have other suggestions to find the lost emails.

I back up the computer every week. Instead of going back to the time before this happened, is there any way to look at the files of the back up to maybe pull out the inbox from there? I don't want to restore an entire backup because I have a lot of work I did in between

If the inbox folder was compacted, where does all the info go? What is the process of compacting a folder?

Compact removes deleted messages from folder files. If antivirus conflicts with the compact process, it is possible to lose the entire file - it would be very unusual to lose individual messages and be left with a usable folder..

Regardless, I think you are well past the point where any compact related files are left from the period where the inbox went bad.

Just get from your backup the Inbox file that has the most messages, put a renamed copy of that in the "Local Folders" directory, then copy the message out of that renamed folder.

In your screen shot of the account settings I see that you have renamed "Local Folders" to "ArtandFraming123". Do you use "ArtandFraming123" (aka Local Folders) to store messages? Now I wonder whether you have recently created a "global Inbox (Local folders)" for your "artandframing123@s......net" email address. This would explain why you can see only recent messages for this account. Can you show a new screen shot of the server settings for "artandframing123@s......net", this time after having clicked on the "Advanced...." button next to "Message Storage" (see image) to open the "Advanced Account Settings" window (my second screen shot)

These questions shouldn't hinder you trying to proceed with Wayne's proposal.