How did you 'delete' / empty the Trash folder: * you accessed the webmail account for email address via a web browser and emptied the server 'Trash' folder? * the server auto emptied the webmail account Trash folder? * you used eg: a phone to access email on server and emptied the 'Trash' folder? * you have another PC/laptop (2) that uses Thunderbird and has an imap account for same email address and you emptied the Trash folder ? Thus when you opened up Thunderbird on PC (1), the imap account synchronised with server and the 'Trash' folder now appeared empty. Imap accounts can only see what is stored on server which you can also see via webmail account. Do you have a backup of profile ?