Restore deleted items through recover deleted items in Outlook Web Access (OWA)
To restore deleted items in webmail, you need to use Internet Explorer as browser, in Firefox you have not all functionalities.
Once logged in on the webmail, go to "Options" and select "Deleted items".
Here you will find an overview of all deleted mails since creation of the account.
In this way you are able to restore e-mails in the folder "Deleted items", and import them again in your inbox from the "Deleted items" folder.