Check to see if a password is stored in Thunderbird: * Menu app icon > Options > Security > 'Passwords' tab * click on 'Saved Passwords' button * click on 'Show Passwords' button. Each account will have: * either a line starting with 'mailbox://....' line if you have a pop mail account, * or a line starting with 'imap://....' line if imap account * and a line starting with 'smtp://....' line for the outgoing smtp. * If you use Oauth for authentication method then you would see a line starting with 'oauth://....' Can you see the lines for you mail account? If no, then they are not stored in thunderbird. This file may have been effected with loss of data when computer crashed. All mail accounts will have a password. When Thunderbird needs to access the server, the server has to authenticate that it is the correct account, so it requires a username and a password. The username is usually the full email address. Passwords are created or modifed or reset in the webmail account which you access via a browser. They are not created in Thunderbird. If you cannot remember the password, then there will be a 'forgotten password' link where you try to logon to webmail account. If the email address is supplied by your Internet Service Provider, then you will need to follow the instructions at the 'Forgotten Password' link. If you set up an email address using a free service like gmail, then they will usually send an email to another of your email addresses or a text message to a phone number which you previously gave them for such purposes. That email or text mesasge will have a code which you use to gain access to the account. Then you can reset the password. Once a new password has been set up in the webmail account, logout of webmail and then test new password by logging in again to webmail account. Once you can do this, you can enter the new password in Thunderbird when prompted and make sure to select the checkbox for Password Manager to store the password.