Bad mood. Why?

Normally, every person is able to cope with his/her anxiety, even those people who experienced some phobias or stressful situations. Let's be realistic and accept that not every life situation is to make you be worried, depressed or hot-tempered. Your first bad mark is not the reason to spend the rest of your life in your room regretting your pitiful life or feeling shame (like some parents try to influence you). In addition, it is not the cause to get away your friends for a long time.
Bad mood can be the result of your growing up. The matter is that in the teen age both boys and girls get some changes in their bodies. The puberty hormones (testosterone for the boys; estrogen and progesterone for the girls) influence your body and cause ups and downs of your mood.
There is the psychological reason of your bad mood. The matter is that in your teen years you try to understand your "ideal nature" and your "real nature", the difference and similarity. Confusion and conflicts are the logical results of your desire to define yourself as a person and occupy your place in a group, the society or your family.
There is not anything tremendously bad in that. It is to be over in some years. If your parents do not understand your mood changes, try to explain them that it is temporary, especially if you know different reasons of it beside your stubbornness and childish behavior.