Please notice that HOW you backup files makes a difference as to doing a READ of the files. Exactly Which method did you use?
One method that can be used does NOT let you get into separate files one the DVD. The DVDs are part of a backup set that is meaningful only to the backup/restore program.
So, did you try to do a full restore using the backup program to restore the PC to its former system and file set that you preserved with the backup program?
Pardon me for repeating. I have some trouble with communication in technical terms. The tern 'backup' is used much to freely. What you have may be an 'image' rather that a systematic backup.
Some methods that are called 'backup' do not allow a ready means of restore or view of a single file. This was documented in the 'Viata Complete PC Back' link. Did you use some other backup method? One that does allow you to see the files individually as if the DVD were a standard volume of the Operating System.
I do hope this is of some help.