Are you using Oauth authentication? You may do better by changing server from imap googlemail dot com to imap dot gmail dot com. If you are not using Oauth, here is that info:

Here are the basics:

- change your security authorization to Oauth2 (do this for the incoming server settings and also for the Outgoing (SMTP) server - two places - remove the password entries for the account (remove the entire entries both incoming and outgoing) - that password info is at Tools>Preferences>Privacy&Security - click 'saved passwords' Then click 'show passwords' then highlight the rows with incoming and outgoing gmail servers and click DELete. - check to ensure that TB is set to accept cookies (that setting is just above the Passwords section) - Google will then step you through the authentication process for your PC.

I don't know what helped but your suggestions alone didn't. I finally got it back with a combination of 2fa and a back up email..with your hints included. Thank you for your time and effort.

I was glad to assist. Please mark this closed so it is removed from open issues list. Thanks much.