To recover deleted items that no longer show in the Deleted folder, please use the following instructions. The screenshots in this article are from Outlook 2013, your version may look slightly different. This guide is for recovering deleted items in the Outlook application. For recovering deleted items in Outlook Web Access (OWA) please see How to recover deleted items in OWA.
1. Go to Deleted Items
Select Deleted Items in the list of folders on the left hand side of Outlook.
2. Open the Recover Deleted Items menu
Click the Home tab at the top of the screen, then select Recover Deleted Items From Server below.
3. Recover the deleted item
Look through the list of emails to find the item you wish to recover. Click the email you wish to recover, select Restore Selected Items and Click OK. To recover multiple emails, press CTRL as you click each item.
The recovered emails will appear in your Deleted Items folder. From here, you can move them back to your Inbox/another folder.