How to be happy again?

Try to stay away from the things that you don't like
Remember your happy moments from the past
and try to find the source
for example, in the past I used to be happy if I can watch tv cartoons
and play computer games, so I look for them again
Personally I prefer to play, have fun
Try to choose subjects that you like if you go to college
Try to find a job you like if you decide to go to work
I believe happiness is the ultimate goal
So find things that you enjoy doing
I recommend playing
star wars jedi knight jedi academy (jka)
star wars knights of the old republic (kotor)
Get as many light side points as you can while playing
and choose the light side option when you have the choice.
After playing through the game you gain knowledge of being a jedi
if you wish to continue the path of the jedi
try to find the book star wars the jedi path
and also take some sources from the bible
to find the goodness in life
to be a good person so that the happiness and joy shines from within
Hope this helps