First, start a new game or load one from your memory card. Then quit back to the main menu. If you go to Start, you'll have the option of Current Game or New Game. Select New Game and it should warn you about losing unsaved progress. Select Yes and it will bring you to the difficulty selection. Instead of selecting one, just press the back button to go to the previous menu, and this time select Current Game instead. When it brings you to the mission selection screen, it will have all the missions on it! Note: Keep in mind that, by selecting New Game, you ARE losing your unsaved progress. It's just like starting any new game, but at any level you want. So you will not have any of your ratings or guns from the game you quit from.