This article explains how to recover Yahoo mail messages that have been lost or deleted.

When you delete an email, it goes to the Trash folder, where it stays until you empty the folder. You can quickly recover a message if it's still in your Trash folder. Here's how:

Select the Trash folder in Yahoo Mail. You will see this in the navigation pane on the left side of the Yahoo Mail screen.

Click the check box next to each email message you want to recover.