|Restore by copying your "outlook.pst" backup file (you did make a backup of it didn't you?) to this location:|
C:\Users\<your account name>\Appdata\Local\Microsoft\Outlook
(overwrite the existing "outlook.pst" file that's already in there)
If you haven't got a backup of that file, well that just shows you why backups are important.
You need to enable "Show hidden files & folders" to be able to see the "AppData" folder.