YOU SAID:

dad left to get milk and he never came back

INTO JAPANESE

お父さんは牛乳を買いに出かけ、二度と戻ってこなかった

BACK INTO ENGLISH

Dad went out to buy milk and never came back.

INTO JAPANESE

お父さんは牛乳を買いに出かけたまま、戻って来なかった。

BACK INTO ENGLISH

Dad went out to buy milk and never came back.