Get value of non public member

How do I get the value of display name of a non public member. What i have tried...

 private void TabGroup_SelectedSourceChanged(object sender, FirstFloor.ModernUI.Windows.Controls.SourceEventArgs e)
    {
        var a = ((ModernTab)sender).Name;
        var b = ((ModernTab)sender).SelectedSource;
        var c = ((ModernTab)sender).Links.Where(q => q.Source == e.Source);
    }

    private void TabGroup_RequestBringIntoView(object sender, RequestBringIntoViewEventArgs e)
    {
        var x = ((ModernTab)sender).GetType().GetFields(System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance);
        var m = ((ModernTab)sender).GetType().GetMembers(System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance);
        var mylist = sender.GetPropertyValue("linkList");
       // var q = ((ModernTab)sender).Links.First(x => x is ListBoxItem && ((ListBoxItem)x).IsSelected == true)
    }