YOU SAID:
I don't know what to have for lunch today
INTO JAPANESE
今日は昼食のために持っているかわかりません
BACK INTO ENGLISH
I do not know that you have for lunch today
INTO JAPANESE
私は、あなたが今日の昼食のために持っていることを知りません
BACK INTO ENGLISH
I do not know that you have for lunch today
Come on, you can do better than that.