That is unusual. All I can guess is there may be an error on the file. The name of addressbook is abook.sqlite. You can check in profile by these steps: - click help>troubleshootinginformation - scroll down to 'profile folder' an click 'open folder' - you will now be in profile and that file should appear. If so, something is preventing thunderbird from recognizing it. If the file is not there, I have no idea to offer.

Hmmm...there is no 'profile folder' I have uploaded screenshot of what I've found. Then when I click on that I get the next screenshot I have sent. Where should the abook file be?