I always feel sad I don't know why. I try a lot of things but nothing I mean it nothing makes me happy?

I have felt the same as you and I do have a certain answer to this, but the thing I did was to keep going and try to find something that made me happy. Try finding things out of your comfort zone and maybe something will click with you in a way you didn't expect. And even if it doesn't, the experience of doing something new still matters.