Start by scanning your hard drive for .pst files (files with a .pst
extension). Those files (or in your case more likely, file) will contain all
your information (that type of file is the Outlook data file and all e-mail,
contacts, calender entries, etc, are stored there - assuming you use Outlook
as a stand-alone application and not in conjunction with a Exchange mail
server).
Once you have located the file, and put it in a location where you are
comfortable with it (I do back up these files on a regular basis, and do not
use the MSFT default location since that is hidden too deep), go to the
bottom of the folder list you should see to the left in your Outlook window.
At the bottom, there is a (blue) link to "Data File Management..."
Click the "Add..." button and then locate the .pst file you found earlier.
Voila, all your previous info is there - ASSUMING that you did not delete the
good ol' pst file...