If you deleted the contacts in an address book, there is an add-on that may recover them, but if you deleted the address book, the only way I know is to restore from a backup. Barring that, it's also possible, with the help of an add-on, to scan mail folders and extract email addresses and place them in an address book.

Where do I obtain the add-on to recover my address book contacts?

What is the name of the add-on and where do I get it?

https://support.mozilla.org/en-US/questions/1201671

https://support.mozilla.org/en-US/kb/installing-addon-thunderbird