you can do something like this, you switch between the states in your game loop
enum GameState {Menu, Play, Help}
GameState currentState = Menu;
while(true) //game loop
{
switch (currentState )
case : Menu
inputMenu(); updateMenu(); drawMenu();
if(buttonPlay) currentState = Play
if(buttonHelp) currentState = Help
case : Play
inputPlay(); updatePlay(); drawPlay();
if(buttonMenu) currentState = Menu
if(buttonHelp) currentState = Help
case : Help
inputHelp(); updateHelp(); drawHelp();
if(buttonMenu) currentState = Menu
if(buttonPlay) currentState = Play
}