YOU SAID:

I know not why I am so sad.

INTO JAPANESE

私はとても悲しい私はなぜ知りません。

BACK INTO ENGLISH

I do not know very sad I why.

INTO JAPANESE

私はなぜとても悲しいかわかりません。

BACK INTO ENGLISH

I do not know why so sad.

INTO JAPANESE

なぜ悲しい私は知りません。

BACK INTO ENGLISH

Why sad I do not know.

INTO JAPANESE

なぜ悲しい私は知りません。

BACK INTO ENGLISH

Why sad I do not know.