When you say 'Find' are you talking about 'Search' ?

If you selected the 'Trash' folder and then used the 'Quick Filter' Search option it should locate email. But if you were using the 'Global Search' then perhaps you have not selected those folders to be included in the 'Global Search'. Right click on eg: Trash folder and select 'Properties' There is a checkbox that needs to be selected to include in Global Search results.

Are you talking about an imap or pop account? Do you mean your 'Sent' folder is empty ?

Have you tried to repair the 'Sent' folder to see if this is an index issue.

• Right click on 'Sent' folder and select 'Properties'
• click on 'Repair Folder' button
• click on 'OK'

check the Account Settings > Copies & Folders to see if the correct folder is selected. Try using 'Other' and selecting the 'Sent folder on the imap account' then restart Thunderbird.

Also check: Log on to your webmail account using a browser. Is the 'Sent ' folder empty on server ? If yes, then Thunderbird cannot display something which does not exist.

Did your Anti-Virus product quarrantine the 'Sent' folder ?