About 10 days ago, Thunderbird automatically installed its latest version on my machine. Since then, Thunderbird won't show any folders or messages in the window. Also, most of the menu items act as if they are grayed out even if they aren't. For example, I'll click on Tools, Account Options, and then nothing will happen (even though the options are black and not gray). The weird thing is that Thunderbird is still recognizing the connection to my gmail account because when Thunderbird is open, I'll still get pop-up notifications for new incoming messages. Screen shot of the empty Thunderbird window and the popup notification for new gmail message is attached.

I've tried uninstalling and reinstalling Thunderbird. That didn't work. Neither did activating a previous restore point on Windows (I'm on Windows 8.1). I tried starting Thunderbird in safe mode but that didn't do anything either. I have no idea why the Thunderbird window doesn't show any email folders or why I can't execute most of the menu options. I've sunk hours into trying to figure it out, and I haven't been able to find any articles online that address this problem. Please help! Thank you.