おかなかった

didn't do in advance

→ おく
おか do in advance; leave ... done + なかっ Negative past + Past tense
auxiliary · past indicative Rare #40,892
didn't do in advance As an auxiliary, it follows a て-form and indicates that something was not done beforehand or in preparation.
JA: 旅行の前にホテルを予約しておかなかった。
EN: I didn't book a hotel in advance before the trip.
Conjugation of おく