re: Thunderbird would not accept my password, so I deleted the account and immediately reinstalled it with a new password.

This would be the most drastic method of updating a password. Perhaps all the regular methods did not work. This would not be of any consequence for an imap mail account as the emails are held on the server. Was this a pop or imap mail account which you removed?

when you say 'lost all my local email files', Are you talking about the removed mail account local files - meaning folders that used to be displayed for that account locally on your computer. OR Are you talking about folders kept in 'Local folders'

Thanks for your response. I am very untechnical, however I believe my original account was POP. I was unable to reset my password so I took this "drastic action" thinking that my file structure was local to the PC rather than the server, and therefore would be permanently on my hard drive and could be easily restored. By file structure I mean the list I generated over many years which was located at the left of the screen ... inbox, outbox, sent, deleted etc, and then "local files" below which I had created sub files for my old emails after they had been replied to. I cannot believe that I was allowed to delete my account without being warned about loss of data! Is there any hope of my getting these old emails back?

First of all, you can delete a stored password in Thunderbird to force it to ask you for the new one. I'm always puzzled by anyone taking such a drastic action as deleting an account as a way of resetting it.

Stuff stored in Local Folders is yours and is entirely independent of actual accounts or servers. So if that has vanished, something else is going on. Deleting an active email account can't rationally affect what is stored in your Local Folders. (Unless maybe you had managed to drag a folder from an IMAP-connected account into Local Folders?)

Right, once upon a time, you didn't have an account. You created it, used it and it collected messages for you. Now you choose to delete the account. What do you expect the messages stored in it to do next? They disappear, of course.

Actually, the files they were stored in are not automatically deleted, but merely removed from view. After all, these files are associated with an account you have decided to stop using.

If the removed account used POP, you can use this add-on:

https://nic-nac-project.org/~kaosmos/mboximport-en.html

to re-import the messages from the now hidden account and everything should be as it was before, but they will import, usually, into Local Folders, since they don't "know" which, if any, of your existing live email accounts would be most appropriate. After importing them, you can move them yourself, of course.

If it was IMAP, then you don't need to do this importing thing, as your messages are all stored on the server, waiting to re-appear when you re-connect your mail client to the server, by simply adding the same account again.

You could try this: Tools > Account Settings > Server Settings for the mail account at the bottom you will see 'Local directory' click on 'Browse' button loctae the old pop mail account directory. click on ok

Close thunderbird, wait a few moments for background proceses to finalise and then Restart Thunderbird.

If this does not work then use the ImportExporttools option as advised by Zenos.