Look through your sent messages. If you ever sent a message to that contact, you'll have the email address.

Actually, Christ1's reply was reasonable, and I did check my Sent folder and other relevant folders where I should have stored an email, but couldn't find the one I was seeking.

Which raises another question: Can Thunderbird become so overtaxed that it drops messages from folders? Or maybe it's my brain....

If you install MoreFunctionsForAddressBook, it can restore deleted contacts.

So I downloaded and installed the Add-on. . . and had to restart TB, which emptied my trash folder (where the deleted contact was presumably housed). And, when I visited the add-on after installation, I found nothing relating to recovery of any kind. It's mostly about importing and manipulating vCards, which I'm not interested in. So, no, it didn't help. I'll keep the add-on for a bit, in case someone can tell my how its recovery function is supposed to work.

Deleted contacts are not moved to the Trash folder.

Did you right-click on an address book and choose the Recover/Restore option as shown in the picture attached to my reply? The add-on is working properly here to recover deleted contacts.

Ah. I did not see the screen capture in your earlier reply. This time, I did it correctly, and I'm pretty sure the correct contact was restored. (I was a little apprehensive at the "...will be restored with a random-character name" part, but relieved to find I didn't need to restore/replace the entire address book manually.

So, thanks for sticking with me! ELM