My bookmarks have disappeared. Refresh does not work. Have looked at the Help tab but nothing seems to work to recover them. Ideas anyone?

Try a system restore.

The same happened at me when I had my bookmarks with
Google Chrome as Browser. What I did was click on the yellow star at top left of page and then when the box came up clicked on "other bookmarks". This returned my bookmarks to me. If you set your bookmarks up in Google Chrome that is what will restore them for myou. If you set them up in another Browser I don't know the answer I'm only ignorant.