wordpress stoped me to add links to the menu and also add widget to the widget areas

something wired happened to my wordpress site and I hope you can help me in figuring out what can cause the issue.

I am running the Multisite and some how when I add a widget to a sidebar or a widget area the widget does not show up and if I go back to the appearance/widget page the widget I added does not show as saved and I have the old set up of the widgets area. A similar problem is happening with the menu. I can not add new links to the menu. This problems started after I switch form a normal installation to a Multisite (to use Marketpress and is “Like eatsy” functionality).

Is it possible that I have limitations in place for adding menu items or widget for the site I added to the multisite?? I am sign in as superadministrator so that should not be an issue, or maybe I have set the site with some limitation and I have no idea on where to set does thing.

thanks for your help hope that you can help me in figuring out the problem and how to solve it.