update images, fix media playing when clicking back button

Author: insomniachi

Screenshots/home.jpg

@@ -172,7 +172,7 @@ public void ExitApplication()
 
     public void AppTitleBar_BackButtonClick(object sender, RoutedEventArgs e)
     {
-        NavigationFrame.GoBack();
+        ViewModel.NavigationService.GoBack();
     }
 
     public void AppTitleBar_PaneButtonClick(object sender, RoutedEventArgs e)