Archiving your email will create a separate PST file that will contain the email that you have chosen to archive (by date).

1. You can still view and search for emails in the Archive Folder (archive.pst). Just make sure where you know the location of your archive PST when you set your archive location. To open the archive PST, from Outlook , goto File > Open > outlook data file

2. If you archive emails and want to undo it; drag the emails from the archive folder to the email folder you would like to place it back to.