The account is only removed when user requests it. I suggest you click do this (assuming Windows): - on desktop, enter %appdata% in search bar and press enter. - that should open to the appdata\roaming directory - if there is a folder named thunderbird, click it to see if there is a profiles folder, and in that a profile. - next, if your account was IMAP, look in the imapmail folder to see if account is listed - if POP, look in the Mail folder

If the account is there, you can install thunderbird and reclaim the account without reentering it.