Click 
Trash in the Folder List.
Select the item, then click Undelete at the top of the Item List.
Click Trash in the Folder List.
Select the item, then click Undelete at the top of the Item List.
The item is moved from your Trash to the folder from which it was originally deleted.
Related Topics
To delete an item you received
To delete or retract an item you sent
About the Trash