Hi Duckfarmer27, could you fill in the picture for me about what you copied to where? In particular, I'm guessing:

Source:

C:\Windows.old\Users\you\AppData\Roaming\Mozilla\Firefox\Profiles\some.folder

Destination:

C:\Users\you\AppData\Roaming\Mozilla\Firefox\Profiles\some.folder

Is that correct?

Firefox doesn't automatically detect new folders under Profiles. It is only aware of the profile folders listed in these files:

• C:\Users\you\AppData\Roaming\Mozilla\Firefox\profiles.ini
• C:\Users\you\AppData\Roaming\Mozilla\Firefox\installs.ini

So assuming you copied the folder into that neighborhood, the next step will be to add it to profiles.ini so Firefox can find it. There are a few methods for doing this, from manually editing the file to using the Profile Manager to create a new profile pointed at that folder. I'm not sure which is safest/fastest.

Note: in order to edit .ini files it helps to set Windows to show all file extensions. This article has the details: https://www.bleepingcomputer.com/tutorials/how-to-show-file-extensions-in-windows/

I guess if the new profile created when you reinstalled Firefox isn't important, you could copy the installs.ini and profiles.ini from the Firefox folder under Window.old to the live Firefox folder.

I would be cautious to copy an entire profile folder as this can cause issues.

You can copy files like these with Firefox closed to the current profile folder to recover specific data.

• bookmarks and history: places.sqlite
• bookmark backups: compressed .jsonlz4 JSON backups in the bookmarkbackups folder
• cookies.sqlite for the Cookies
• formhistory.sqlite for saved autocomplete Form Data
• logins.json (passwords) and key4.db (58+) or key3.db (57 and older) (decryption key) for Passwords saved in the Password Manager
  if you only have key3.db then make sure to remove an existing key4.db
• cert9.db (58+) or cert8.db (57 and older) for (intermediate) certificates stored in the Certificate Manager
  if you only have cert8.db then make sure to remove an existing cert9.db
• persdict.dat for words you added to the spelling checker dictionary
• permissions.sqlite for Permissions and possibly content-prefs.sqlite for other website specific data (Site Preferences)
• sessionstore.jsonlz4 for open tabs and pinned tabs (see also the sessionstore-backups folder)

You can use the button on the "Help -> Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page.

• Help -> Troubleshooting Information -> Profile Directory:
  Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder
• http://kb.mozillazine.org/Profile_folder_-_Firefox

Jscher2000 - Thanks much for providing the solution. I know just enough to be a problem with this technology.

I was solving this as step 1. Now to research and perform the exact same save for Thunderbird - currently lost all my emails. I'm going to assume it is similar from my research so far.

Again, thanks for saving my bacon on this one.

The Thunderbird folder is more like:

\AppData\Roaming\Thunderbird