Formal:
* Je ne suis pas heureux/heureuse. (I am not happy) - This is the most direct and neutral translation.
* Je suis malheureux/malheureuse. (I am unhappy) - This emphasizes the negative feeling.
Informal:
* Je ne suis pas content/contente. (I am not content) - This is a more casual way of saying you are not happy.
* Je suis pas content/contente. (I'm not happy) - This is even more informal and colloquial.
* Je suis déçu/déçue. (I am disappointed) - This suggests that you expected something better.
* Je suis triste. (I am sad) - This expresses a deeper sadness than "not happy."
To express stronger feelings:
* Je suis furieux/furieuse. (I am furious) - This means you are extremely angry.
* Je suis écœuré/écœurée. (I am disgusted) - This suggests that something has made you feel sick to your stomach.
The best way to choose the right phrase depends on the context and the intensity of your feelings.