You can easily restore a deleted file from the Trash by moving it from the Trash to another folder. Restored folders are automatically moved back to their original location. However, you will not be able to restore the item if you have emptied the Trash since deleting it - it has been permanently destroyed.
To restore an item from the Trash:
Click on the icon of the item that you want to restore in the Trash area on the bottom-right of the window. The folder or file will be automatically returned to its original location.