First, you must reinstall Office.
Then you can configure Outlook to use the same Outlook Data File (PST file)
you were using before instead of the new blank one it created when you
installed Outlook:
- Go to Tools > Options > Mail Setup > Data Files > Add...
- Add the PST you'd like as your new default, then Close > OK to exit the
Options dialog
- Go to Tools > E-mail Accounts > View or change existing e-mail accounts
- Select the PST you just added in the "Deliver New e-mail to the following
location" dropdown (it will most likely appear just below the current
default Personal Folders file) > Finish
- Exit and Restart Outlook
- You can now close the previous default PST (R-click on that pst folder
while in Folder View and select "Close <foldername> Folders"). If you have
any information in your former PST that you'd like to transfer to your new
default PST, you can drag and drop from one to the other before you close
the old one.