Backup?

Give this a try and let us know the results.
File
Export
Accounts

to a finger drive

Then import to the email client

Yes please let us know. If it works you have been helped and you, through me, will help many more.

Me bad.

I thought that it was only the email
These settings are in Windows Live Mail
Windows Mail
and
Outlook Express

They are in other clients, but maybe not under file.

Use this: MozBackup - Backup tool for Firefox and Thunderbird

Its very handy and I have used it many times to back up and restore Firefox and Thunderbird.

Try this. Go to Computer > C: > Users > [your user name] > app data (you may have to change settings to show hidden files and folders) > Local. From there, look for something like Mozilla or Thunderbird. If you find Mozilla, then open that folder, then go to the Thunderbird folder. Copy everything within that folder to a usb drive. After you reformat and reinstall Thunderbird, go to that same folder. Replace everything in it, with what you copied from the old install. I did this with Google Chrome before and it worked perfectly.

When you return if you have that happy face, it is all worth while.