The addressbook is within the profile. if you deleted the profile prior to installing a new release of Thunderbird, that act would have deleted the addressbook. If I am misunderstanding, please provide more information. Thank you

Thanks for your response. I downloaded the update and didn't erase anything. There was Personal Address Book (empty) Address Book (there were several addresses there but no Personal Addresses) Collected Addresses (empty). You can see my problem. Now I can't send any emails without having email addresses.

Puzzling. Thunderbird doesn't delete such files, so it may be somewhere. Here's a suggestion: - click help>troubleshootinginformation - scroll down to 'profile folder' and click 'open folder' - exit thunderbird - you are now in the profile. note the files prefixed with 'abook' - those are the addressbooks. note the names and sizes - now, click back one folder and you should be in the 'Profiles' folder that lists all profiles - see if there are other profiles in that folder. if so, click each one and investigate presence of any 'abook' files. Are they bigger than the ones in the active profile? if so, those may be your missing addressbooks. If in doubt, post screenshots of the abook entries in active profile and of the other profile and we can attempt to advise.

(NOTE: in addition to looking for 'abook' prefixed files, also look for 'history' prefixed files - those would be the collected addresses. The existance of a large history file would be a strong indication that you have found both the old personal addressbook (abook) and collected addresses.)

Thank you very much for your help. My son has now resolved the problem (at last). As you can see from my original posting, I'm somewhat of a luddite as far as solving these problem.

Thank you again. I'm going to show my son your response(s) so he can understand your point.

Thank you for the feedback. I'm glad that it worked out. :)