According the Help topic here http://www.toodledo.com/info/help.php?sel=13
Be careful with deleting tasks, as there is no way to undelete them. If you accidentally deleted a task or think that a task was deleted by a third-party application, you can check your "Recently Deleted Tasks" list. This is located in your account settings at the bottom of the page.The "Recently Deleted Tasks" used to be at the bottom of the Account Settings page. Now it's at the top left.