They say time changes things, actually you have to change it yourself

Have you ever felt that if you could go back in time you would do it better? That everything would be better if you could make a small change in the past. Have you ever thought that your life would be so much easier to get through if you do it twice. well you shouldn't coz going back isn't going to make anything better. harry goes back in time to save his parents. will it work?