New Norton Antivirus won't open my backup files made by former Norton program

 I had a major computer crash 2 weeks ago and had to reload all of my apps after a reboot.  I have most of my data files, but not my apps.  My backup used to be done to my external hard drive using Norton backup, but I cannot now open the backup because the type of Norton software provided by comcast has changed, and no longer provides backup software????Surely I am not the only one that cannot open their backup files created in Norton Business Suite.

Does anyone have a solution to this and/or a way to work with the backup files?

FYI, the reason I need the backup file is that my data from quickbooks for some reason is missing, and I need to try to retrieve it from my backup file. 

HELP!