YOU SAID:
a person did not find his shoe.
INTO JAPANESE
人は自分の靴を見つけられませんでした。
BACK INTO ENGLISH
One couldn't find his shoes.
INTO JAPANESE
トムは自分の靴を見つけることができなかった。
BACK INTO ENGLISH
Tom couldn't find his shoes.
INTO JAPANESE
トムは自分の靴を見つけることができなかった。
BACK INTO ENGLISH
Tom couldn't find his shoes.
That didn't even make that much sense in English.