Do you have files like prefs-1.js, prefs-2.js, prefs-3.js.... in the profile folder? If so, rename prefs.js to prefs.old (with TB closed), rename the newest prefs-N.js to prefs.js, restart TB, and see if the setup is recovered.

https://support.mozilla.org/en-US/questions/1360261

I have 1 file called prefs says it is a java script file. When I double click on the file name I get a Windows Script Host box. It show the full script but there is no place to change the prefs.js. Which is at the end of the script. I can not find any prefs-1 files.

I changed my preferences to allow hidden files. the full prefs.js showed up. I changed it to prefs.old.

I restarted my computer. Thunderbird program still loads blank. I did a complete search of my computer and found another prefs.js file in a different Thunderbird profile folder. I changed that file to prefs.old and restared my computer.

A new prefs.js file showed up in the second profile. So I now have a prefs.js file and a prefs.old file. And the Thunderbird program still loads blank.

I did not file any prefs-1 files in my computer search.

If the prefs.js in the current profile is missing the account details (open the js file in a text editor such as Notepad), and there are no prefs-N.js files, you can try replacing the damaged prefs file with one from another profile or profile backup. But if none of those options are available, you will have to add your accounts. It will probably be possible to recover 'lost' data such as local mail and address books.

Doing regular profile backups or just backups of critical parts will prevent issues in the future.

I have no idea what you are talking about. I am not a "computer" person. I have used Thunderbird since it started and this is first time I have had any problems. Are you telling me my emails are gone?

I need help. I have a backup. You talk about profiles, on the "damaged" program that is currently on my computer, there are 3 profiles. When I look at the backup, is there a particular profile, and when I find it do bring over all of the prefs and delete the prefes in the current program?

Rename the prefs.js file in the current profile folder to prefs.old, with TB closed. Copy prefs.js from a backup profile into the current profile, then restart TB and see if the setup is restored.

I just re setup the old accounts. Shut off TB restart. It eventually filled in the folders. Click on each one. For address book. "If you do a search in the c:\users\<yourid>\appdata\roaming\thunderbird\profiles folder, you may find abook.sqlite and history.sqlite. These are the technical filenames of the addresssbook and the collected addressbook. You can import them with tools>import>importfromafile. This sometimes happens, that thunderbird creates a new profile and some content is left behind. No, this does not happen to everyone and is likely a glitch wherein an update was interrupted by another program, such as an antivirus product."

This might help. search for "abook.sqlite". Found it in a file, C:/windows.old. look for last oldest.