Personal folder in outlook deleted

In Outlook click on Tools, then Services.
Once you're in Services click on the ADD button and you will be given options for you to install. Click on Personal folder and that should install what you are looking for.
Once you've installed the Personal folder, close Outlook altogether and restart it.

Good Luck

Just wanted to add to the previous messages:
If your user already had an active personal folder with address books and emails, you do not have to create a new personal folder. Just point to the exsiting file. It should have a ".pst" extension. If you are not sure where it is. Just search for it before adding the personal folder again. If you have more than one, look at the date and size. It will tell you which one it is you are looking for. After adding, just restart Outlook. After re-opening, it might tell you: "Personal folder option is changed, do you want to recreate icons and settings?" just say yes and it will completely reinstate all settings for that user.