There are many reasons why a coach will bench you during a game. A common reason for a coach to bench a player may be that he/she may not be as skilled as the other players on the team. Coaches want to win games and that means putting the best players out on the court at the times of the game where they will be the most successful.

If you are not receiving much playing time during games or not playing during the times of the game when you would like to be playing I would suggest you (not your parents) talk to your coach in a private setting. When meeting with the coach say to him "I am not receiving the amount of playing time that I like, is there anything I can do to get more playing time, for example skills?" Believe me a coach would rather talk to you with this kind of attitude than a defensive parent. In past years I have had numerous parents come to talk to me, when I tell them what their child needs to improve on they get all defensive and think I am a terrible coach, however I have had 3 players come talk to me themselves and the ended the season as starters. 

If your coach tells you that you need to improve on certain skills ask him if he has any suggestions for what you can do at home. You can also look on youtube for drills or hire a local Personal Basketball Trainer, a Basketball Trainer can also work on other aspects of your game that need improvement that your coach may not have noticed.