To recover mail which is deleted before 10 months

When you delete messages in Yahoo! Mail, they go to your Trash folder. If you delete a message by mistake, you'll be able to find it in Trash and move it back to your Inbox or another folder. Just remember that messages in your Trash folder can be deleted at any time, without warning.
To permanently remove the contents of Trash, click "Empty" next to Trash in the left navigation bar. Next, a window opens asking "Are you sure...?" Click "OK" to delete or "Cancel" to close the window.
After messages are emptied from Trash, they're permanently deleted from the Yahoo! Mail server and can't be recovered.