Gary, you can try creating a new profile with a custom path that matches the original profile's path, to register a profile with the desired path. You'd then need to delete the newly created profile folder's contents and replace them with the original folder's contents.

Some more detailed steps, and please read before attempting anything.

1. Go to the original profile path in File Explorer
2. Copy the original folder to a backup location, for safety
3. Rename the original folder in the original location by appending "_original" to the folder name
4. In Firefox go to about:profiles and press "Create a New Profile"
5. Follow the wizard, making sure to specify a custom path for this new profile that is identical to the original profile's path (as it was originaly named before you appended "_original", obviously)
6. In about:profiles, make sure that the newly created profile is set as the default profile
7. Fully exit Firefox
8. In File Explorer, delete the contents of the newly created profile folder and replace them with a copy of the contents from the original profile folder that you renamed in step 3 (and again, I'd recommend copying rather than moving items in order to maintain untouched backups)
9. restart Firefox

If all has worked as it should, Firefox will open with your original profile data.

Thanks TechHorse, however, your steps are too vague to understand well enough to use. I've chosen to totally uninstall FF and ALL the profiles and garbage related to FF. I do have a backup of the profile I saved back in November fearing FF screwups. Reinstating this Nov25 profile is better than starting from scratch. Is there a way to import it into a brand new download/installation of FF?

lolaiii, when you re-install Firefox it should create a new profile.

See this article for the steps to replace this new profile with the backup: https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles

Note, some users might find that this doesn't work 100%, so if you find an issue after following the 'total replacement' method, then another possible avenue is to create a new profile then restore only specific individual files from the backup to the new profile.

See this article for the steps to create a new profile: https://support.mozilla.org/en-US/kb/profile-manager-create-remove-switch-firefox-profiles

And see this article for a list of the individual files that you may wish to copy into the new profile folder (with Firefox closed, naturally): https://support.mozilla.org/en-US/kb/about-your-important-data-and-their-files