YOU SAID:
私は昨日何を食べたかを思い出せない。
INTO JAPANESE
私は昨日何を食べたかを思い出せない。
BACK INTO ENGLISH
I can't remember what I ate yesterday.
INTO JAPANESE
昨日何を食べたか思い出せない。
BACK INTO ENGLISH
I can't remember what I ate yesterday.
That didn't even make that much sense in English.