It will help if you provide some detail on your problem. For what it's worth, here are steps for transferring from one Windows PC to another. here is the info in brief steps: '''BACKUP''' # ensure thunderbird is not running on old PC # enter %appdata% in search window on task bar and press Enter key # this should open windows file explorer in Appdata\roaming folder # highlight the Thunderbird folder and copy to external media '''RESTORE''' # ensure thunderbird is installed, has run at least once on new PC, and NOT running # enter %appdata% in search window on task bar and press Enter key # you should be in Appdata\roaming folder , copy&paste the exported Thunderbird folder there. This will prompt to overwrite an existing folder of same name. allow it # start thunderbird and all should be there