Rebuild a .PSE file for a Photo Book

Working in Elements 15

Created a Photo Book - All was working well the system was saving properly, there was a folder that had all the individual .PSD files saved.

During a Save AS function the .PSE file must have been corrupted,

Now when I open the book there is data missing on the pages, but when I  look at the individual .PSD files all is correct

So my ??????

How can I rebuild the photo book with all the .PSD files so I can continue to finish and print out the Book?

or

Do I have to start over from scratch

Thanks

Dave