YOU SAID:

My father left to get the milk He has not returned

INTO JAPANESE

父は牛乳を取りに行ったが帰ってこなかった

BACK INTO ENGLISH

My father went to get milk, but he didn't come back.

INTO JAPANESE

父は牛乳を買いに行ったが、帰ってこなかった。

BACK INTO ENGLISH

My father went to buy milk, but he didn't come back.

INTO JAPANESE

父は牛乳を買いに行きましたが、帰ってきませんでした。

BACK INTO ENGLISH

My father went to buy milk, but he didn't come back.