If I understand it well you have lost emails of year 2018.

Do you think you can try to perform a research. They might be hidden somewhere in TB.

Lost emails from feb 2017 to 6th of july 2019 as can be seen in the attached inbox list snapshot.

As suggested searched all folders in TB; could not find them. Had setup filters to move certain emails matching the filters to folders created by me. Those emails are available in those folders. The emails that were in the inbox have vanished.

I would first suggest to close TB and then backup you Profile Folder :

Profile Location Summary %APPDATA%\Thunderbird\Profiles\xxxxxxxx.default\

%APPDATA% is shorthand for the C:\Users\<username>\AppData\Roaming\ folder, which depends on your Windows user account name.

Than try to repair it as mentionned here : Repair manually

wich I think is the same as this : Open TB, right click on a folder with missing mails, Properties, then "Repair folder" (if my translation is right)

Took the backup of the profile folder as soon as I noticed the missing emails. Also had run the repair on the inbox folder as suggested. Still the emails are not found!

My knowledge in Thunderbird is too poor I think. Can you open the folowing file in Notepad : %APPDATA%\Thunderbird\Profiles\<strangeAccount.name>\ImapMail\Imap.yourMailProvider\INBOX (I supposed your account is in Imap) Then check if there can be a 2018 date ?

The account is pop3. Traced the "Inbox" file in the below folder and opened it. No emails with 2018 timestamp found!

%APPDATA%\Thunderbird\Profiles\<strangeAccount.name>\Mail\mail.<myMailProvider>\Inbox

I think the emails are lost, no way I will be able to recover them now. Should have taken regular backups or Archived emails.