When Hashem looked for Adam in Gan Eden and called out to him, "Ayekha?" Adam hid himself. He felt that since he had sinned in the only commandment he had been given, how could he dare face his Maker in his nakedness. He had no legitimate excuse, and therefore hid from Hashem in shame.
Surely, we cannot presume that Hashem didn't know where he was. The question was a way of addressing Adam so as not to frighten him, and a way to help Adam start the conversation. He wanted Adam to realize thoroughly that even though he had sinned, he was still acceptable before Hashem and Hashem still sought him.
The very question, said the Mashgiach, HaRav Meir Chodosh, has a very deep significance: Ayekha is like Eichah - this is a dirge on Man who fell into disgrace. Hashem did not accuse him directly by asking him why he had eaten from the Tree but asked, rather, "`Where are you?' What happened to your great status? Look how far you have fallen."
Hashem wanted Adam to realize the ruination in sin but to know that he could at least show remorse. Adam heard Hashem's voice in the Garden and hid from himself. Hashem came to call him to task, to make him regret and acknowledge his sin.
"Ori refers to Rosh Hashonoh" because the Day of Judgment is designed to illuminate a person's path before him, to bring him to contemplate his sin, show regret and repent. The Day of Judgment is a beacon of light for every person to draw him closer again to Hashem, because on this day, Hashem is closer and more accessible to His creations. He stands by each individual and enables him to draw near more easily.
The greatness of the Jewish people expresses itself in that they realize that the significance and purpose of a day of Hashem's judgment is to effect a closeness to Him, and this is what gives us a chance to begin the dialogue.
On Rosh Hashonoh, Hashem invites us, as it were, to present ourselves before Him. He calls out to us on this day, even though the distance is so vast. Without His call to us, we could not presume to stand before Him in our iniquities.
This is a very special day designed and charted for us to stand and plead for our lives. But we must prepare ourselves by introspection. At least during these two weeks preceding that Day of Judgment...
