I understand, having been down that road myself. Thunderbird is a stable bird, so it's hard to really kill it. First, I suggest creating a backup so that you won't lose anything. To do that:

  - exit TB
  - copy c:\users\<her id>\appdata\roaming\thunderbird to anywhere else for safekeeping 
  - now, start TB.  If you see obvious duplicate folders that are not directly related to an account (such as INBOX), try just deleting the folders. I presume the Outlook Express folders are in Local Folders, so that approach may apply there as well. For duplicate input files, highlight each and rightclick and look at properties. I think the 'real' one will show in location with something such as '....Mail/accountname/inbox  and the clone will appear as something else. Delete that one. 

If you don't like that approach and want to assemble a new profile yourself, you could do this: - first, do the above recommended backup anyway. Things can always go wrong. - click help>troubleshooting information, scroll down to 'profile folder' and click 'open folder' - exit TB. you are now in the profile. the addressbook is abook.sqlite and any saved addresses from incoming messages will be in history.sqlite. copy both elsewhere - for messages, POP message folders are in Mail\accountname\ where you will see such as inbox, inbox.msf, sent, sent.msf etc. duplicates will have a different name and I'm guessing you'll spot the duplicates. Copy the ones you need. This approach also applies to IMAP accounts, which are in Imapmail folder. This is the simple process. Copy nothing. When IMAP accounts are opened and there are no message folders, they are recreated automatically. - for non account folders, look in Mail\Local Folders folder. Here again, you will see message folders and can probably recognize what is good and what is not. Copy what is good. - at this point, you have the parts to reassemble a profile. OR... you can delete the duplicate parts and restart TB and see if all is okay. -FOR POP ACCOUNT: if you reassemble the profile and set up the POP account again, do NOT include password yet. You need to copy all the saved message folders and any other files that were in the account folder PRIOR to entering password. Otherwise, Thunderbird will start downloading messages that have already been downloaded. - there, done. I hope this helps.

Thanks David, I will give the second option a try. Already had backed up to a flash drive but have been unable to delete the 'protected' folders even though they are duplicates. Will post my results using your second approach. Bob

Since I had deleted the pop account and let Thunderbird re-create using imap, I found the files I wanted to backup under Outlook.office365.com within the imap mail folder. After putting copies on a flash drive, using RevoUninstaller I uninstalled Thunderbird in order to start over. No joy! The profile was still there so when I downloaded and installed Thunderbird everything came back like the uninstall never took place.

CORRECTION: I re-ran RevoUninstaller again only this time I selected the more advanced scan for leftover items and over 33,000 files were found which I deleted and the profile was included so perhaps I am back on track. Now to start from scratch. Will post results...

After uninstalling Thunderbird and downloading it to start over - as I was creating the email account got the message "configuration found in Mozilla ISP Database". So some of what I thought was gone actually was re-instated. At this point the only files I was able to import from the flash drive was the address book and history which were both sqlite file types. Tried copying the inbox and outlook express import files into the imap folder and local folders but they do not show up in Thunderbird.

Any idea how to restore the inbox and all the stored emails in folders (Outlook express import) without importing the profile? The latter will I'm sure just put me back at the beginning with duplicate inboxes, etc.

I suggest this: - highlight Local FOlders - rightclick and select the import-export entry and, from there, the import mbox option - then, select one of the outlookexpress folders (but not the .msf entry) and that should import it. - repeat the above for each folder to import. - if you need to move some messages to IMAP, it gets messy. First, import to Local Folders. Then, if not many, you could highlight a few at a time and click the 'copy to' context entry. If many, then I suggest creating a filter to copy to the imap folder and delete the local folder after completion. This can be problematic as imap was not designed for high volume uploads.

I did not see your suggestion in time so while I was able to get the old inbox back I never could get all the emails saved in folders to show up. The folder name appeared under Local Folders but when opened it was blank. So I did a system restore hoping to get things back to where it was before all my feeble attempts to resolve the issues. After doing the system restore now Thunderbird does not open - get the "couldn't load XPCOM" message. Guess I need to re-install Thunderbird....

this may help: https://support.mozilla.org/en-US/questions/1360766

David, I did follow the process as outlined in the link you provided. Thunderbird then opened with just three entries under Local Folders: Inbox, Trash, and Outbox. I then successfully imported the address book. However, when I attempted to import messages from the saved profile, not only did I get all the inbox messages but also a whole string of other folders with their own set of inboxes, etc. I did not expect that since I chose just the "Mail Messages" option and unchecked the "Accounts and Settings", "Address Books" and "Calendar" boxes. Since most of those newly created items in the folder pane were empty I was able to delete them. The imported inbox items are in a separate Inbox, not in the newly created Inbox but we can live with that.

The remaining problem is the missing email folders she had saved, which were in the Outlook Express Import folder. That folder appears in the folder pane but is empty. Where would Thunderbird store all those files and folders? If they are in the profile does that mean I need to start over and import the saved profile?

Thanks, Bob

It seems you chose to select the import profile option. My suggestion had been to import the mbox option, which lets you select each folder separately. I suggest trying that option for the outlookexpress files.

Well I am confused, as usual, because I do not find any import-export option when highlighting Local Folders either from within the Thunderbird folder pane or within the profile - Mail / Local Folders. Perhaps that is no longer an option with the latest version I am now running, 115.9.0, or am I looking in the wrong place for the Local Folders you reference?

My apologies. I was referring to a popular addon, importexporttools NG. click tools>addons to install it.

David, The addon is working but will take awhile to process all her files. It was what I needed all along. Thank you for your help and patience! Bob

You're most welcome. I had been working at same time with two other people who needed the importexport tool and I had forgotten to whom I had explained how to get it. I regret that my oversight caused your delay. Anyway, I'm glad all is working out ok. :)

All's well that ends well - happy wife; happy life!