If the job was completed, it will not be found in the Workorder/Unfinished Jobs button. Another option is to remove the checkmark from the use Automatic File naming. This will provide a button called open to the right of the Mapping Job button. Use this to locate the original .fgp file. Once map has been displayed, you can tapt the File Menu and Export Log. This will give you the option to export as an ArcView Shape file or .GPL file extensions.
Hope this extra information along with Mitch's post gets you what you need.