You can verify that all is lost by these steps: - at desktop, enter %appdata% in search bar and press enter. That takes you to file explorer and the appdata\roaming folder. If there is a folder named Thunderbird, your email data 'may' have been preserved. Click the folder and see if there is a folder named profiles. If so, check that folder to see if profiles are present. - if no thunderbird folder, then you're starting over. Just reenter the account info to set up the email accounts.