This is the 17177th most frequent Turkish word.
çıkmamıştı
"Had not come out" or "had not exited."
In this sentence, "çıkmamıştı" is used to indicate an action (leaving the house) that had not occurred up to a certain point in the past.
Yağmur nedeniyle evden çıkmamıştı.
Due to the rain, he/she had not left the house.
Here, "çıkmamıştı" is implied as "not published" in a broader sense, showing a state that had not been realized previously.
Kitap basılmamıştı, bu yüzden elimize ulaşmadı.
The book had not been published, hence it did not reach us.
In this context, "çıkmamıştı" refers to the action of a movie being shown in theaters, indicating it had not happened yet.