YOU SAID:

I left the monkey in the refrigerator by accident.

INTO JAPANESE

たまたま冷蔵庫に猿を置き忘れてしまいました。

BACK INTO ENGLISH

I happened to leave the monkey in the fridge.

INTO JAPANESE

たまたま猿を冷蔵庫に置いていきました。

BACK INTO ENGLISH

I happened to put the monkey in the fridge.

INTO JAPANESE

たまたま猿を冷蔵庫に入れました。

BACK INTO ENGLISH

I happened to put the monkey in the fridge.