On the home screen, touch and hold in a blank spot until you see the Wallpaper, Themes, Widgets, Home screen settings appear along the bottom. Open home screen settings and enable "Add apps to home screen".
Not sure what you mean by "Menu screen".
If you see the Apps button on your home page you can click that to go to the app screen. If you don't see that button, you can swipe up from the bottom of the screen to see the app screen. The app screens show all installed apps. If you have folders set up, check for the missing ones in the folders.