Greetings LeviBalint I once helped this method: When you delete a message, it is not actually deleted, but is marked as deleted and will not be removed until the action 'squeeze' (compact) will be done, so most of the letters might be restored. By default, Thunderbird e-mail is in the "C:\Documents and Settings\{username}\Application Data\Thunderbird\Profiles\{random number}.default\Mail\Local Folders". If the desired letter is in the 'Inbox' folder, the file will be called Inbox, if, for example in the subfolder 'Inbox-> Personal', whereas in the subfolder 'inbox.sdb' will be 'Personal' file. Recovery Just in case the copy of the file, so you can restore in case of failure 1. Close the Mozilla Thunderbird program; 2. You must open the file for editing in any program-editor (notepad advise not to use, because it hangs when opening large files); 3. Find the deleted message such as by date and sender; 4. The header line will letter type 'X-Mozilla-Status: 0008' or 'X-Mozilla-Status: 0009'; 5. Replace the code 0009 or 0008 to 0001, save the file; 6. Remove the index file, it should be named as the same as the file with letters such as 'Personal.msf'; 7. Start Mozilla Thunderbird and refer to the folder in which to make changes, create an index (this may take some time), and you'll find your restored email. I hope this advice has helped you with your problem.

Thank you very much for your fast answer. But unfortunately this doesn't solve my problem either. My emails are not in the folder you specified, not under local , not under roaming, nowhere. And it's not about one or two emails, my entire Inbox is missing. I also use a mobile app for mail, I'll give it a shot there too.

LeviBalint, As I understand it, "Inbox" is missing in the program. A hard drive you watched your profile e-mail client? (Path to the folder with the profile I have indicated above). if there is still something is, then you can restore them using the procedure. If there's nothing, then unfortunately the letter is not restored.