Although you haven't given us specific information about the TYPE of disc you're trying to un-protect, if you're looking at CD-R or DVD+R discs that have been burned and finalized, then you can't write to those particular files again.. They're permanent on the disc, at least while they're on the disc.. OF COURSE, if you copy those files to you computer, then RIGHT click on the file, choose "Properties", then UNCHECK the box next to "Read only", you should be able to edit the files..
If you're dealing with a CD-RW or DVD-RW and it's coming up with the same message, it may be corrupted.. Try the same method of RIGHT clicking on the drive in "My Computer", choose "Properties" and see if "Read only" can be unchecked.. If not, then the disc is corrupted or has become too old to read correctly
There ARE registry entries that can block writing to discs but if this computer is yours and you haven't made those registry changes, then it probably isn't the cause..
Hope this helps and let us know more.
I'm running Vista(32) & I'm having problems with the CD/DVD drive, I keep getting tha "this disk is write protected" message, so I can't even re-format them.
How do I "Un-write protect" a disk?