Too Many Message Boards

A problem today I use pdf sewing patterns and the files up until today when I open them show the layered icon and I can choose which sizes I want to print off.
 today no layering
I have opened Adobe Acrobat reader DC  gone to view - show/hide- navigation panes
all the navigation panes are grey and inaccessible
I use Chrome
Appreciate any help/suggestions

Ok sorted by renaming and saving the pdf and the laying all restored in renamed file. Don't know how that works lol

that's good to know thanks.