Restart Thunderbird with add-ons disabled (Thunderbird Safe Mode). On the Help menu, click on "Restart with Add-ons Disabled". If Thunderbird works like normal, there is an Add-on or Theme interfering with normal operations. You will need to re-enable add-ons one at a time until you locate the offender.

That does nothing. I click on it, and absolutely nothing happens. I think my T-bird is corrupted, but I don't know how.

I have no add ons or anything, that I know of. This is just a straightforward install, I have mostly gmail addresses. It always works otherwise. Until this last update.

hold the shift key while clicking to start Thunderbird. then continue in safe mode when prompted.

This worked, I disabled all add-ons, extensions, and plugins. THANK YOU!!!!

Interesting, I told you use safe mode. Nope. I tell you to do exactly the same thing via a different route and you say thank you it worked

So what add-ons do you have?.

I had 2 plugins from Intel Identity Protection Technology, which were already disabled, and I had Shockwave Flash and Silverlight, which I disabled. Not quite sure what they're doing in TB. There was something in Extensions that I did not knowingly install, and I deleted it once I was able to, so I don't remember what it was, nor did I recognize it. I have no themes or add-ons, nor did I previously.

My guess it was called lightning and it was the calendar component.

"Interesting, I told you use safe mode. Nope. I tell you to do exactly the same thing via a different route and you say thank you it worked"

I hope you don't think I just wasn't listening to you, I did exactly as you instructed, but nothing happened. None of the menus were functional until you instructed me how to open TB in safe mode. That also restored the message view on the right.

Thanks, again, it's working perfectly now!

That sounds very familiar. I think you are correct.