HI, for this type of question, it's not an easy answer because a lot of it depends on your hosting company, etc. If you are hosting the site yourself, then we could perform the task for you through our premium support policy. However, to walk you through a backup / restore of your website without knowing much about your configurations (IIS version, windows servers,etc) is not possible.
Perhaps you can go to DotNetNuke forum and find the correct steps for backing up and restoring your website there. -- David