What password are you talking about? The Primary (Master) Password? The sync password?

https://support.mozilla.org/en-US/kb/reset-your-primary-password-if-youve-forgotten-it Resetting your Primary(Master) password will remove all of your saved usernames and passwords. This is a security feature.

Resetting the sync password, or changing its e-mail will remove all data from the servers. The username and password are used to create the encryption.

This is a security feature. https://support.mozilla.org/en-US/kb/ive-lost-my-firefox-sync-account-information

• I've lost my Firefox Sync account information - What to do
• I’ve forgotten, or don't have access to, my Firefox Account email address

Note: Only the data on the servers is cleared. The profile data is not changed or removed.

I have the hard disk of the old/ damaged computer . . .

You will need to plug the old hard drive into the new system as an external drive. Once that is done, you can then Copy files from the old profile to the new one.

1) Use these links to find the old profile

https://support.mozilla.org/en-US/kb/how-run-firefox-when-profile-missing-inaccessible

http://kb.mozillazine.org/Profile_folder_-_Firefox#Navigating_to_the_profile_folder

https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles

https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles

2) When you are ready, we can start moving parts of your old data and Copy it to the new profile.

First; open your file browser to the New profile;

Type about:support<enter> in the address box.

Under the page logo on the left side, you will see Application Basics. Under this find Profile Folder. To its right press the button Show Folder. This will open your file browser to the current Firefox profile. Now Close Firefox.

Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder

Linux: Under the page logo on the left side, you will see Application Basics. Under this find Profile Directory. To its right press the button Open Directory.

Second, open another file browser to the old profile folder on the old hard drive

Warning ! ! Only Copy the files you are told. We will avoid anything that might cause problems. Here is the list of files;

cookies: cookies.sqlite Do not bother. Cookies will be created when you return to the website. However, you will have to log in everywhere. And you may lose any settings that websites store on your computer.

extensions(add-ons, themes): it would be better to download them fresh. If you need to remember what add-ons you had, open the extensions sub-folder and look at the .xpi files

logins.json and key3.db [v58+]key4.db : These are the password files. Copy Both !

persdict.dat : custom dictionary - words you added to the dictionary

mimeTypes.rdf [v55+]handlers.json : What to do with what type of file.

places.sqlite : History and Bookmarks.

prefs.js : Your settings. Note: If you were having problems, this could be contaminated.

cert8.db [v58+]cert9.db and possibly cert_override.txt : Stores all your security certificate settings and any SSL certificates you have imported into Firefox. If removed, the cert8.db, cert9.db file will be replaced.

search.json.mozlz4 : file stores the user-installed search engines that are available in the Firefox v47+

search.sqlite file and searchplugins folder store the search engines that are available in the Firefox Search bar before Firefox v47

Copy these files from the old to the new. You may get a message that the files already exist. Choose to over-write for each file.

Update. I found a youtube video that was helpful. I was able to restore all the data of the former firefox account.

The video here https://www.youtube.com/watch?v=QaD3QnnsQFU

That was very good work. Well Done.