Backup did not work

Hi: I used Nero 6.6.0.16 to backup my drive about a year ago . Will i wipe my drive , tried using backup disk (5 DVD ) got to 3rd disk it said could not find data insert disk 3 will i tried all 5 same thing . So i used XP disk fresh install , is there a way to get the dat. file off the DVD when i right click , open with , there is nothing that will open them .
Thanks Jerry

Try it using a program called ISOBuster.