The OneDrive icon has always been at the top of my Navigation pane.  I performed a Windows Update this morning and now OneDrive is not there anymore.  I can find the Onedrive folder, and the contents seem to be intact.  I've looked on a number of sites and they suggested editing of the registry - but I'm loath to do that - surely this should not just happen!  

I am running Windows 8.1 on a very simple home network.  I have a laptop running 8.1 and that still has the OneDrive icon on the Navigation pane.