About three days ago Thunderbird stopped working for me. When I opened Thunderbird all my previous settings, account information, emails, and calendar events had disappeared. The application appeared to have reverted to an almost original blank state, and prompted me to set up a new email account. After a bit of checking, I discovered contacts information remained. So I used a previous backup copy of the "prefs" JScript Script File from a backed up Profiles folder. This restored previous settings, accounts, and email folders but Thunderbird was still unable to receive or send email. I attempted to remove an account, so that I could set up a new one, to make sure that Thunderbird was using the correct account information to retrieve email (from gmail). However... Thunderbird will not remove accounts. I am able to click on the "Account Actions" button and select the option to remove an account, but after confirming "ok" nothing happens. I've tried uninstalling and reinstalling Thunderbird. But Thunderbird will still not send or receive messages, and still will not allow me to remove an account. I've tried turning off the calendar add-on, although it was working before all this happened. According to files and records, it appears there was an update to Thunderbird at the same time it stopped working. When I uninstalled Thunderbird, two Thunderbird files were listed and one was dated the day the issues began. Thunderbird also has problems closing and sending crash reports. How can I edit account information to ensure the correct information is being used by Thunderbird to download and send mail? How can I remove and re-add an account if the removal and add account options are broken? I've tried several ways to access account options and settings within Thunderbird, all result in the same inability for Thunderbird to respond. (Apologies if this appears to be a re-post of the original issue. This post includes more information than the original).