Did you see if it's listed in the "Backup" folder? By default the Backup folder is located at: \Program Files\Altiris\Workflow Designer\WorkflowProjects\Backup
There should be sub-folders in the \Backup folder of all your projects as long as they made backups at least once and of course the "Do Backups" option is checked in your Edit Tool Preferences, which I believe is checked by default.