The first thing to try is click the hamburger (3 bar) icon, Tools/Import...Address Books...vCard file, and select the .vcf file. Open Address Book and see if the new address book looks OK.

OF course, now that you tell me, I all of a sudden remembered. MAybe you can provide some additional help.

I'm trying to set up another email account in T-bird for my wife; it's a gmail account. When I enter her name, email address and password, T-bird tells me that the password is incorrect and it is not. Any ideas?

If you have set up two-step verification on the Gmail account, then you will have to create an app-specific password for third-party programs like TB.

https://support.google.com/mail/answer/1173270?hl=en

I didn't set up anything like a 2- step process. Am I missing something? I set up my own account without this headache; just wondering what I've missed.

I'm not sure what the problem might be; perhaps there's some clue on this page:

http://kb.mozillazine.org/Using_Gmail_with_Thunderbird_and_Mozilla_Suite

starting with the section 'Less Secure Apps'.

I have a Gmail account, but don't access it with TB. But I do use TB to access AOL and Hotmail accounts, and they set up and work very well.

Your above suggestion got me a little further. The Gmail account shows up in T-bird but when I click on it I'm asked for the password and I type in the correct one but still get the invalid password message. I've done this once before for my own address and don't remember having this problem. Would that double verification, or whatever it's called be sending a code to her iPhone/iPad that needs to be used instead of the regular password? I'm not asked for anything but "password", nothing indicates something other than the password is needed.

The export function from iCloud creates one single .vcf file with all the addresses in it. If you click on it on the desktop, it starts displaying each and every address as a separate vCard. However, "Tools/Import...Address Books...vCard file" doesn't do anything.

If a phone or tablet is signed into the Gmail account at the same time when you try to access it from TB, I suppose it's possible it fails, even if 2-step verification isn't enabled. Although, I don't have problems accessing my Gmail from different devices (the main reason for using this type of account).

Try setting up the account Offline (File/Offline/Work Offline), then go back online and see if the passwords works.

For the contacts, install MoreFunctionsForAddressBook (How to install), then import the vcf file from Address Book/Tools/MoreFunctionsForAddressBook/Actions for contacts/Import vCard/vcf. I know this works for multiple vCards, and it may work for a single vcf with multiple entries.