If you opted for Thunderbird to save passwords then they are here:

In Thunderbird

• Settings > Privacy & Security
• Scroll to 'Passwords' section
• Click on 'Saved Passwords' button
• Click on 'Show Passwords' button

As passwords have been altered via webmail, you will need to alter the stored password for both incoming and outgoing smtp. You will see two lines - one will be either 'mailbox:// account... for pop OR imap://account... for IMAP and the other will be smtp://account...

• Right click on relevant line and select 'Edit Password'
• Clear all data and then carefully enter new password.
• Once both lines have been correctly updated...click on 'Close'

I would suggest at this point to Exit Thunderbird - wait a few moments for all preferences to be updated to relevant files then start Thunderbird. Thunderbird should then check all accounts using the new password.

I knew all that, but the problem is not just about the passwords: there are no downloading credentials at all, no pop3 etc, and I cannot find a way to put them back. I am thinking of deleting all my accounts, and then setting them up again using the automatic account configuration tool, and hoping that does the trick. Incidentally smtp credentials are there, but I cannot in fact send any messages.

Justr to be a bit clearer, I see the line beginning 'smtp' but the line beginning 'pop', which you mention, is not there at all

Justr to be a bit clearer, I see the line beginning 'smtp' but the line beginning 'pop', which you mention, is not there at all

In stored passwords - The incoming line for a pop account start with 'mailbox://....'

If you have no line starting with 'mailbox://account.... then no password was stored. In this case you would expect Thunderbird to try to access server and server ask for password. Hence the prompt for password pop up window.

You could try completely removing all stored passwords: Click the "Remove all" button, then the "Close" button then restart Thunderbird and it should prompt for password, at which time you enter the new password you created and select the checkbox to remember password before clicking on OK.

If that does not work then try the following: In Thunderbird

• Help > Troubleshooting Information
• Under 'Application Basics' section - half way - Profile folders - click on 'Open Folder'

A new window opens showing the contents of your profile folder.

• Exit Thunderbird now this is important

There have been many cases where password is NOT stored and you are NOT getting the prompt for password and the 'pkcs11.txt' is the only file that needs to be deleted. This usually occurs maybe after a major update or if you move the profile from one operating system to another. So first only try deleting this one file.

• pkcs11.txt

Start Thunderbird and see if offers password prompt, enter password, select checkbox to remember password before clicking on OK.

Please note: if you have any clean up product like CCleaner, WiseCleaner or any anti-virus product that offers clean up of files, then I strongly advise you do not let these products clean up anything in your profile name folder as they have a habit of deleting session files, passwords, etc and you do not want this to occur in Thunderbird.