This is outside the scope of these forums.

If possible go by the physical location you bought the phone from or your mobile provider's store. They may be able to assist, though it sounds like a long shot.

It's my computer that was redone not my phone. I've had thunderbird for years. No way to talk anyone? I'm an old lady

This was asked on the Firefox for Android forum. Thus I answered assuming that you were on a mobile device.

Moving this question to the Thunderbird forum.

Thunderbird address books are on your local drive. Since they were not there when your device came from the factory, resetting it to that state removes them. Did you make a backup before resetting your computer? Load the address book from that.

Thanx

This tells you how to make a backup for next time. https://support.mozilla.org/en-US/kb/profiles-where-thunderbird-stores-user-data

In the outside case the address book files survived the reset they are .mab files. You could do a Windows search for that file type