Unable to access data after backup onto DVD (Nero 6)

I backed up some pictures (bmp, jpeg, tiff, gif) onto a DVD-RW, as well as some zip files and other files from my old computer using Nero 6 (It had Windows XP SP2 on it). When I went to restore these onto my new computer, it won’t recognise the file formats (it says they’re not valid), and I can’t get any files off the DVD-RW. Has anyone got any ideas as to how I can access these files, and if there is any software available to access the files? When I did the backup of the files (as a data DVD), no error message came up.

Lesson #1: You are not “backed up” if you have only one copy of your data.
#2: DVD-RW discs are unreliable.

What mode did you use to burn the files? Was it a normal DVD-ROM compilation? OR did you use InCD? Multisession or not? Disc closed or not? What does Nero say about the disc properties? Does it show it as blank or used?

You could try a program like ISOBuster to read the disc, or try it in a different reading drive.

What mode did you use to burn the files? It was in Nero ROM (make a data disk). Was it a normal DVD-ROM compilation? OR did you use InCD? Nope, I didn’t use InCD (It was a normal DVD-ROM complilation) Multisession or not? No multisession Disc closed or not? Yes, the disk was closed What does Nero say about the disc properties? Does it show it as blank or used? It says that there is just over 900kb free, with 3500 (approx)kb available (the amount that was burnt was just over 2.6gig)

Are you able to use something like CloneCD, or similar program to rip the disc to the HD, and then mount the image?

Clonecd will handle read errors, whether this works for you is a totally different matter.
If programs (or zip files containg programs) are corrupted, they will behave unpredictably, or not compress.