Jim, don't know if this helps, on my Chrome I have "other bookmarks" folder on the bookmark toolbar (although mine is on the righthand side), if I right click that it gives the option of Bookmark Manager, after left clicking that it comes up with bookmark manager "organise", click that and it allows Import/Export to html file.

I wonder if you have accidently exported them to a file somewhere, if so you should be able to import them again.

Not that I know anything, but it's just a thought!