Please respond to my request.

''re : I have transferred from Windows 10 to Windows 11'' Do you mean you had a computer using Windows 10 and you have used the upgrade option to change to Windows 11 ? OR do you mean you have two computers, old one using Windows 10 and new one using Windows 11 ? Did you need to reinstall Thunderbird? If yes, where did you get the download/installation of thunderbird ? This is important because the official website download from this link: https://www.thunderbird.net/en-US/thunderbird/all/ would put the Profile in an easy accessible default location as mentioned in all the various Help Articles etc , but if you got the latest Thunderbird via the Windows App Store then it gets more complicated as Windows stores everything in a completely different location. Did Thunderbird ask you to create a mail account? If yes, this tells me you are using a new profile. This info combined with previous question would tell me where it got created. In Windows C drive, do you see a folder called 'windows.old' ? If yes - click on it to see the contents do you see this 'Thunderbird' folder this in that location: * C:/Users/Username/Appdata/Roaming/Thunderbird Does that 'Thunderbird' folder contain 'Profiles' folder which has profile name folders that contain abook.sqlite files of good size ? Does the 'ImapMail' or 'Mail' folder contain mail account name folders ?