I regret you have this serious issue; there will be much to do here. My suggestion first is to contact your email provider to confirm whatever is needed to secure a new password. If your credit cards are with your bank, contact them immediately, as they should be able to confirm who you are because they can verify your mailing address-- an that may also be true for the email provider. Once you have those two, you can start contacting various persons who will need to know of the loss. Going FORWARD: My suggestions: - establish a cloud backup service. It doesn't need to be a fancy one, just one that does daily backups of key files. - some possible candidate files to back up would be

  - backup of browser profile, as it has passwords embedded
  - backup of a a file with email passwords. there is a free utility at https://www.nirsoft.net/ that makes file of browser passwords and thunderbird passwords. 
  - a text file of credit card numbers and the 800 number for help 

Be SURE to create a password for the cloud backup that you will remember. As as aside, Thunderbird does not have any offline storage of your accounts, so we cannot assist here.

One more thing: buy an external drive and backup software and backup the PC at least monthly at minimum. I have used Ashampoo's Backup Pro for many years and it's been perfect for me, although I'm sure there are many others. That also protects you in case the computer crashes. In today's world, there is no excuse for having no backup.