Mozilla Thunderbird Stopped Working

[KimmerJ]

I have been using Mozilla Thunderbird for several years, but most recently I cannot get my Gmail messages to load in Thunderbird.  I get a pop-up message asking to insert my google password which I do, but still cannot load Gmail messages.  I then get another pop-up message stating to go to
https://support.google.com/mail/accounts/answer/78754 (Failure)

Any assistance/help to get me back up on Thunderbird would be appreciated.

[BC_Programmer]

That error would be coming directly from Google, and means that it is misconfigured (or they've changed it so that however you were connecting before no longer works).

Check the account configuration for Server Settings and verify that it matches up with what is on that page.