YOU SAID:

why you sad? i don't know

INTO JAPANESE

なぜあなたは悲しい？知りません

BACK INTO ENGLISH

Why are you sad I do not know

INTO JAPANESE

なんで悲しいのかわからない

BACK INTO ENGLISH

I don't know why I'm sad

INTO JAPANESE

なぜ悲しいのかわからない

BACK INTO ENGLISH

I don't know why I'm sad