Restore your back-up.

When you use IMAP, you have your emails back after entering your mail-account in Thunderbird, because the messages are still on the server of the provider.

@Johann, I suspect (restoring) backup isn't a useful answer here.

4ARC, try starting at the Windows command line with

  thunderbird.exe -P

1. What profiles do you see? 2. And if you see one at the top named "default" what happens if you choose that one?

I picked the top named "default" and started Thunderbird. My accounts and emails were back. Thank you very much. Some of those mails were very important.

I picked "default" and a blank Thunderbird came up -- no accounts, no saved e-mail, no archives. Asked to setup new e-mail accounts from scratch. Seems to have lost everything.

I had all email accounts deleted too - NOT HAPPY AT ALL Sorry, but I think having to create a new profile - and spend hours trying to figure out what is going on/wrong and finding solutions to fix this - is by no means good enough!!! To me it's a failure of Mozilla-TB. Which - until the last update had always been reliable.

'NAIVELY' had I clicked ‘yes’ to update TB - assuming like most software updates it would run without interference - BUT without warning or hints to back up everything first - the update had wiped out my complete profile and address book !!!.

I almost had a breakdown when I found EVERYTING had vanished!!!! Being self-employed with 6 email accounts/addresses, I can not afford to spend hours trying to fix this. In the end I did a system reset/restore but it did not get my address book back. Low and behold I spend in excess of 5 hours getting my customer emails back and accessing new emails. Time that I have lost and cost a lot of money!

However, now every morning TB asks to update - I am drrreading it, Grrr - and click it away. Why can't TB fix this failure?

Question now is: How do I stop TB from updating. I want to keep everything as is and don’t want to spend any more unnecessary time to fix an TB error /failure.

Wayne Mery said

@Johann, I suspect bBackup isn't a useful answer here. 4ARC, try starting at the Windows command line with thunderbird.exe -P 1. What profiles do you see? 2. And if you see one at the top named "default" what happens if you choose that one?

_________________________________________________________________

NOTHING FOR ME! I use a MacBook so this is useless for me and many others who use Macs. But this exact things has happened to me two other times in the past ten years. I try to remember to back up my information on a regular basis but sometimes life gets in the way. But regardless I contacted Mozilla for help immediately each time and got zero, ziltch, nada, nothing - no help whatsoever. Always saying something like 'Sorry. There's nothing I can do.' and 'In the future back up your email app.' I do not believe that there is nothing they can do. ________________________________________________________________________

I picked "default" and a blank Thunderbird came up -- no accounts, no saved e-mail, no archives. Asked to setup new e-mail accounts from scratch. Seems to have lost everything. </blockquote>

I do not feel that Mozilla is taking any responsibility for this Thunderbird Email issue that caused may people to lose everything after an upgrade.

All of the many folders, addresses - a great deal of very important emails that were saved i those many folders gone just like that. I know from my own experience that this problem with Thunderbird's email and folders being deleted with no way to stop it for decades and I have complained about it to no avail. No concern whatsoever. Callous disregard for the problems this caused all of us! We thought that Thunderbird would be a safe place to store mail securely.

None of us can get all of that important information, lots of emails, many, many folders back again nor can we duplicate everything that was being saved. It makes me angry no one appeared to care at Mozilla.

This is your screw up. Mozilla! Take responsibility! Do something to stop this from happening NOW!

It is a common misconception that Mozilla develops and provides Thunderbird - it does not https://wiki.mozilla.org/Thunderbird:Home

Regarding listing and viewing profiles on Mac, an alternative is Help > Troubleshooting > about:profiles from there you can see what profiles are available and access their directories.

My Thunderbird updated overnight last night. It deleted all of my accounts, my address book, and ALL of my downloaded emails. I have tried Windows command line "thunderbird.exe -p". The account that should have all my email is totally empty. The "default" account has 2 email accounts, but no email, and no address book. The 3rd account, which was a backup of old email on an external hard drive is also empty.

Can someone please tell me what happened here? And how can I fix this? I had things stored in email folders that I desperately need to recover.