You were able to post here, so your login here works fine for obtaining support.

As far as Firefox Accounts for using Sync, did you check the Spam folder in your email account to see if the confirmation email ended up there?

the-edmeister.... many thanks for your reply. To recap, I couldn't sign in to ask questions about Thunderbird going dysfunctional on me. Sign in clearly wasn't recognising any attempt to do just that and I was getting no response to the request to do so. Yours is the first reply I have had yet I am surprised I have received this as I have not additionally attempted any further log in. Nothing in spam folder. However, I am now obviously logged in so I will continue elsewhere to correct my Thunderbird problem. Again, many thanks. mckendrick