Its sounds like you may not have permission to edit all pages. If you go to the admin section and click on Set Access Rights you can view and change access rights to pages as well as media files and blocks. Maybe someone removed the admin roles permission to some pages?
I'm guessing what you're missing is the Episerver Quick Navigator. That's added to a page by using "@Html.RenderEPiServerQuickNavigator()" so, first of all, I'd suggest checking whether that line will be included in all of your views. Generally it will be included in your layout so it should appear for all pages however, if you have different layouts for different pages or, if it's included directly in the page view, it could be missing which could explain why the quick navigator isn't appearing.
Another possibility could be that, when you're clicking on your navigation, you're being taken to a different domain where you're not logged in. For example, you might be running the site locally but your dev server is set as the primary host in your site configuration. As a result, when you log in on your local machine (e.g. mysite.local), everything would be fine but, when you click on the link in the navigation, you will be taken to the dev URL (e.g. mysite.azurewebsites.net) where you're not logged in.
Another thing to check is http vs https. Make sure you are staying on the same url scheme.
I work on a sites where I can log onto an https site, but then if I am not careful i switch to http, without the login. (I know there should be a https redirect, and have suggested it to the client)
I am using the latest version of the episerver, I have cretaed the Login functionality, Now whenever i am login with the admin rights , It is showing me the "Edit" tab for the only one page. whenever i am redirecting my navigation to other page that "right side top corner Edit" tab will become invisible .
What am i missing ?
Please guide us .