Did you save the ....appdata\roaming\thunderbird folder? or the profile folder? was this done when thunderbird was running? Explicit details will be useful.

David - You’ve helped me before. Good to have your help again. I saved the %appdata% folder on my HDD per a note I had from you on 13 July. I was very careful to make sure Tbird wasn't running. Even used Task Manager to check. But I must have done something wrong.

Try this: - do screenshots of the appdata\roaming\thunderbird folder and also of the appdata\roaming\thunderbird\profiles folder and send the name of the profile that you saved there. That will help me locate it and suggest next steps.

David - It took me a while to figure out how to do this. Pardon my ignorance! And sorry for the delay! Here are:

Appdata\Roaming\Thunderbird Appdata\Roaming\Thunderbird\Profiles Profile saved on my HDD as Thunderbird in folder Thunderbird Profile 7-15-25

BTW, I don't know why I started this thread under the name "Restore Firefox" when I meant Restore Thunderbird!

It appears you pasted the backup thunderbird folder into c:\users\<yourid>\appdata\roaming\thunderbird. That is why there is a thunderbird folder under the thunderbird folder. - exit thunderbird - copy your thunderbird backup from the external mediat to appdata\roaming\ you will be prompted for an overwrite. allow that. - now restart thunderbird

David - I seem to have forgotten how to get to appdata\roaming\ If i put %appdata% into the search bar and press Enter, it takes me right back to: c:\users\<yourid>\appdata\roaming\thunderbird. Please remind me how to get to the correct appdata\roaming\Thunderbird folder. Thanks, David

You will be in windows file explorer, so click the back arrow in upper left to back up to prior folder.

David - After searching on %appdata% and pressing enter to get to Appdata Roaming, the left and right arrows were grayed out. So I selected Roaming manually and pasted in my saved profile. It copied, overwriting some things. When I brought up Tbird, still just the Account Setup window. What have I done wrong?

The profile may be corrupt. One possibility would have been creating it while thunderbird was running. if the old PC is still available, you might try repeating the process. Otherwise, your profile is likely in the profiles folder. click help>troubleshootinginformation, scroll down to 'profile folder' and click 'about:profiles' - your old profile should be here and you can try to launch it

If everything fails, the contents (addressbook and messages) can still be salvaged.

That’s reassuring. And folders? I’m beginning to think I need a fresh copy of Tbiird. Uninstall, reinstall? Is that possible? The backed up profile should still be good, I’m hoping. Why am I having such trouble with this?

Oh, and BTW … I can no longer access my profile via Help>Troubeshooting Info. I get an error message.

Yes, the old PC is still here. But it may be out of sync with Local Folders which are on my HDD and were used by the new PC before it was erased.

Here is my suggestion:

1. start fresh. Should not need to reinstall, as you have thunderbird and an empty (?) profile
2. click tools>import>import from a file and follow the prompts for addressbook and at the option on formats, select sqlite and then locate and select the abook.sqlite from old profile. That is basic addressbook. Repeat the process to import the collected addresses, which is the history.sqlite file. Those steps will regain your addresses
3. with thunderbird not running, you can copy message folders from the old profile to the new one. Old POP messages will be in the Mail\<POPaccount> folder and any local folders will be in the Mail\Local Folders folder. Ignore the .msf entries. I suggest copying all files to the new profile in the Mail\Local Folders folder. That will leave some POP messages not in the account, but you will have them
4. next, recreate the accounts that you had

For the future, I suggest doing backups periodically. Here are suggested steps to keep:

here is the info in brief steps:

BACKUP

1. ensure thunderbird is not running
2. enter %appdata% in search window on task bar and press Enter key
3. this should open windows file explorer in Appdata\roaming folder
4. highlight the Thunderbird folder and copy to external media

RESTORE

1. ensure thunderbird is installed and NOT running
2. enter %appdata% in search window on task bar and press Enter key
3. you should be in Appdata\roaming folder , copy&paste the exported Thunderbird folder there. This may prompt to overwrite an existing folder of same name. allow it
4. start thunderbird and all should be there

Let me know how the copying goes. If there are problems, please create screenshots. Good luck.

David - I'm overwhelmed with your most recent series of steps that starts with "Here is my suggestion: start fresh ... Let's back up to "The profile may be corrupt. ... Otherwise your profile is likely in the profiles folder. On my "new" (erased PC) here is a screenshot of profile folder > 'about:profiles'. Where would I look for my old profile?

Incidentally, when I click Troubleshooting information > Profile Folder > Open Folder, here is what I get:

I think I see your problem. You installed Thunderbird from Microsoft, which installs the software elsewhere and the proflie is also stored elsewhere. I suggest you uninstall thunderbird, and download from the official site at https://www.thunderbird.net/en-US/thunderbird/all/ and repeat the full process of transferring profile and then it may work.

Not sure how that could have happened. I downloaded both Firefox and Tbird from Mozilla’s own website and made a small donation for each. Nevertheless, I’ll try it. Thanks!

You can see this in your screenshot: thunderbird-MSIX is from MS and the app is in program files\windows apps

I may have logged on to MS to get the Office apps, or to activate OneDrive, and not logged out.