In our daily life activity we see lots of things. We feel happy when we achieve something above our expectations and sometimes we feel sad because we couldn't get which was already not ours.
Happiness is not in getting good marks, getting a new car or winning a lottery. It is inside you. All you need to do is just be happy Feel good always whatever happens in your life.
It is not like that just because you got failed today, you are not going to get a second chance. Definitely you will. Why to feel bad? Think about the situation before it got worst. You were normal right? then why are you getting depressed just because of one bad moment. It is all about our greed from life. We want to grab more and more but we are not enjoying first what we have? So always be positive in life because you are going to get an another chance soon. ;)