The Personal Folder file (.pst / PST) is the place where Outlook stores its data (when you're using Outlook without Microsoft® Exchange Server). Each Personal Folder file contains all of your Outlook folders, including the Inbox, Calendar, and Contacts. You may have a single .pst file (usually called "Internet Folders" or "Personal Folders" in your Folder List), and you may also have an additional .pst file that you use to archive messages (named "Archive Folders"). By backing up these PST files you will be backing up all your Outlook information . The hard part is locating the files...
Right-clicking on the Outlook Today icon found in your Outlook shortcuts, or the Outlook Today icon found in your folder list and then left-click "Properties".
Once the Properties dialog box is displayed, click the "Advanced" button.
The "Path...", indicates where your Personal Folder file can be found.
Write this path down and navigate to the designated folder (Outlook in this example)
OR
use your mouse cursor to copy (CTRL + C) and paste (CTRL + V) the path into Windows Explorer. Then, delete the "outlook.pst" at the end of the path and press the "Enter" key on your keyboard. Explorer will automatically open the folder containing your Personal Folder.
Within the folder you should find an outlook.pst file . Copy and paste this file to a Zip disk or other backup source. It will probably be too large to copy to a floppy disk. If you archive your email, be sure to backup the archive.pst file as well.
Below lists key Outlook files that you may want to back up in addition to your Personal Folder(s). You will need to completely exit Outlook prior to copying these files. Depending upon your configuration some or all of these files may be present in your Outlook directory.
Personal Folders .pst files
Outlook Bar shortcuts .fav files
Rules Wizard rules .rwz files
Nicknames .nick files
Customized toolbar settings outcmd.dat
Customized system folder views Views.dat
Macros and VBA programs VbaProject.otm
Signatures .rtf, .htm, and .txt files
Stationary .htm files
Templates .oft files
Dictionary .dic files
Stores a reference to which extensions (addins) you have loaded. extend.dat files
If you have followed the steps above to backup your Outlook data, restoring is simple. All you do is copy the backup PST file(s) into the folder that you located when you initially backed up your work.
Keep in mind that if you overwrite your existing PST file with your backup PST file, any new data since the time of the backup will be deleted. If you have recent data that is not on the backup copy of your PST file and you don't want to loose the recent data, then you can use the "Import" command to add data instead of overwriting data.