Bad Mood Days...

Everyone feels down and depressed sometimes. Learn how to keep yourself happy.
Talk to friends or parents and tell them how you feel. You will be surprised how this will make you feel somewhat relieved.
Do something you like to do-Read, listen to music, exercise.
Hang out with people that you enjoy.
Keep a journal and write your best memories, achievements, and successes in it. When you feel down down try and read it.
Create a mood chart and try and and figure out what puts you into the bad mood on these certain days. Good Luck !