Unable to read files stored on CD-rom

I have photos stored on CD and the message " the alias 'file name' cannot be opened because the original item cannot be found" keeps appearing when I try to open the file. There are options to either 'delete' or 'fix' the alias but nothing changes. Other photo files on the same CD are okay. All the photos were created using the same software. The original photos are no longer on my Mac laptop as I trashed them in order to free up memory , thinking that they were 'safely' stored elsewhere. Any suggestions as to how I may solve this problem would be much appreciated.