Seriously hard to tell what the problem is.
Try doing a File>Export and choos IDML and open that. It opens as an Untitled document. Don't close your original for fear of forever losing it.
Exporting to IDML is a known cure for repairing corrupt documents, and it might help here.
I would also do a save as to a new name to hopefully get a second copy you can play with.
It would also be helpful, I think if you could show us a screen shot of a page with the layers panel open completely.