Cannot get Mozilla Thunderbird to load. "Not responding".

I cannot get Thunderbird to launch. It acts like it is stuck on perhaps one account and circles keep spinning as if it never can get a few of my tabbed emails open. It keeps saying it "isn't responding." Since this began happening a few days ago, I've stopped the Thunderbird task through Task Manager, I've shutdown and restarted my whole system multiple times, I've updated to the latest Windows platform and made sure my drivers were all up to date... I can't update my thunderbird (if required) because I can't get in in the first place. I have hundreds of emails in multiple accounts under my current Thunderbird. I can't afford to lose all that history. I don't know which version I'm using because, again, I can't get the desktop app to launch. What do I do?