do you get any errors when you open the project? or just no documentation?
the ESD is for element doc and the SCD is for stage comments, are those the two groups of documentation you're wanting to retrieve? what about rung comments? that would be the LCD file.
i'm not sure that you can tell that those files are intact because they contain binary data (not just ascii), but regardless, the easiest thing to try is temporarily moving the ESX, SGX and LCX files out of the project folder and then reopen the project. these files are index files for the documentation and get rebuilt when the project reopens.