Which kind of disk is it? Probably a CD-R or CD-RW?
The problem is, with both kind of disks: they lose data! After a few years, the special gold, silver or blue colored layer starts to make errors (i don't know exactly why, something with organic material or so).
If your pc recognizes your disk (Windows Explorer "sees" the disk), you can try to copy it with (e.g.) "CloneCD". This program can make an image file from your disk, skipping errors.
Note that this could take a long time....
Afterwards, you will have an "image file" (iso-format) on your disk. This iso-file can be mounted in your pc, in a virtual cd-rom station (Daemon tools can make virtual cd-rom stations, it's free)
If your pc DOESN'T recognize your disk, i don't have an option

. Maybe there are scratches on the disk? Did you try another pc, or some laptop or so?