Follow these steps:
- Look below your Inbox to find the 'deleted items' folder
- Open this and search for the deleted item
- If you find the items, right click on the email and choose move. This only applies if you have not purged emails from your 'deleted items' folder
- If you have emptied your 'deleted items' folder, you can click on "Recover Deleted Items from Server" displayed in the Home menu in Outlook
- A list of the items that have not been purged from the email server will show and you can press "Restore Selected Items"