It is possible that the trash file was quarantined by your AV product. Recommend that if you choose to allow scannin of Thunderbird files and folders then do not let AV fix it, always say it should ask what to do. This alerts you an issue with the file, but allowing any AV to fix is likely to cause a problem.

Are you talking about a pop mail account ?

Access profile folder http://kb.mozillazine.org/Profile_folder_-_Thunderbird Exit Thunderbird. All pop mail accounts will be in the 'Mail' folder. Do you see a 'trash' and 'trash.msf' file in the pop mail account profile folder? If yes: delete the "Trash.msf" file, then start Thunderbid. It should repair the indexes and your trash bin.

If this does not work or there is no 'trash' and 'trash.msf': Access same place again and make sure Thunderbird is closed. Create a pair of empty text files. Just create them, don't type anything inside, then change their names : one will be named "Trash" no extension and the second one will be named "Trash.msf". (Or you could copy paste empty eg: 'Drafts' and 'Drafts.msf' files and then rename as advised above.)

Start Thunderbird.

Hello, That didn't work. What I did to fix it was to create a folder called "Deleted" within my "Inbox", and then changed the Server Settings on the mail account to move deleted emails to it. Regards, Tony