Your addressbook is a local file on your PC. Please describe what you were doing, such as an update, or whatever. thank you

the address book in Thunderbird is without any contacts, they all disseappeard at my last windows update. Is there a local file I copy and paste into thunderbird to restore them?

Okay, my guess is that the upgrade created a new profile. Try this: - click help>troubleshootinginformation - scroll to profiles' and click 'about:profiles' - that screen may show more than one profile, an active one and an older one. click the button to open the old profile. - look for a file named abook.sqlite. It would be bigger than your current one and have a recent update date. If found, that would be your lost addressbook. If true, then you should 1) exit thunderbird, 2) copy abook.sqlite and history.sqlite from the old profile and paste into the active profile, overlaying the ones there, and 3) restart thunderbird