Please clarify what you mean by changing the login. Is this a different email address? Did you remove the original account?

I left the original email account set up in Thunderbird but I closed the account at the server. I left all the mail folders, etc. as they were in Thunderbird and assumed they would stay as they were showing the received email history.

I then created a new email account using the Account Setup in Thunderbird. When I was finished doing that I tested the new email to make sure it worked. I believe at that time it still listed the old email account with all folders shown along the left toolbar that shows all the active emails and folders. I closed the program. When I opened it again it still lists my old email name (as well as the new one) but it does not show me the old folders.

There is a gap of time in there where left the machine. I'm sorry I can't verify what occurred. But right now, without intentionally deleting ANYTHING to do with the old account, all that history is gone. I had intended to use the existing mail folders with the new email, but they simply aren't there.

I'm usually not an airhead and have a fairly good knowledge of general computing, and have used Thunderbird for a decade or two, so this was a shocker for me. I would appreciate any suggestions you might have regarding this.

Thanks,

-JR

All I can guess is that the closed account was an IMAP account and, when the account was closed, the messages disappeared. THunderbird attempts to sync IMAP accounts and if there is nothing online, it would delete all that is offline to stay in sync.