You need to look for the profile on your old hard disk, and move it over onto your working hard disk.

https://support.mozilla.org/en-US/kb/profiles-tb

If you really want only the address book, you can copy over just the abook.mab and history.mab files. Other .mab files can be copied, but you'll need to import them using this add-on:

https://nic-nac-project.org/~kaosmos/morecols-en.html

JerrySullivan said

The OPerating system (Win-7) became corrupted on my main PC, so my supplier upgraded the 4 year old machine to a new Mobo etc. and reloaded Win-7. The original "C" drive, with the previous copy of Thunderbird is now on the system as a local drive. I would like to transfer at least the address book from the old copy of Thunderbird to the new install. Which file(s) would I need to move. It should be a reasonably simple disk to disk copy. The plan is to move critical data from the old "C" drive and once that is done, reformat it for use as a local drive only.

Took some doing to find the abook and history files, but when I did, and copied them to the new install, these work fine. There was no great need to import anything else.

Jerry Sullivan