I have just changed my theme layout to Vigilance, which I like, but unfortunately I have now lost my links column and top horizontal navigation access/editing bar too. Can anyone please suggest what might have happened to them and how I can get them back please?
Since your blog is private, we can only guess. My first suggestion is to go to appearance > widgets and if the links widget is not shown as being in the sidebar, drag it back over and into the sidebar. You might also check at the bottom of that page in the “inactive” widgets area as it might be there.
This will happen if you go from a 2-column theme to a three column, or from a 3-column to a 2.