Need help with accessing files on a DVD+rw

I have a DVD+RW disc with about 25 files on it. I was created about a year
ago, and I have been able to add files to it up untill today.
I put the disc into my DVD drive, and the drag to disc Roxio shows "Blank
disc." Try to check the files on the disc, and it comes up blank. I go
into properties, and check and what I get is this: used space 0 bytes
free space 0 bytes
capacity 0 bytes
the entire disc is blue.
I know the files are there, I just cant seem to find them or how to access
I have two boxes with windows xp professional on them, and I get the same
problem with both boxes.
Is there a solution? Can I access these files with out loosing them?
If I could get the files, I could make a copy of the disc.
Thank you, Bob K.