Despite the fact that Gatsby had hundreds of party guests on a regular basis and was well known and popular, he evidently had no close friends. Nick makes it his duty to find people to attend Gatsby's funeral.
Nick is upset that Daisy made no attempts to even leave a note following Gatsby's death. And Nick is astonished that no one else inquired about Gatsby or asked when the funeral was scheduled in order that they might attend. Nick tracked down as many of Gatsby's acquaintances as he could. But no one, not Klipspringer or Wolfsheim, would commit to coming to the funeral. Nick had become increasingly fond of Gatsby, despite his flaws, and found himself to be Gatsby's only real friend. This is why he wanted to "get somebody" for Gatsby. He simply wanted to get someone to attend Gatsby's funeral. Nick wanted to get someone who would show some compassion and reverence for a departed friend.
I went back to the drawing-room and thought for an instant that they were chance visitors, all these official people who suddenly filled it. But, as they drew back the sheet and looked at Gatsby with unmoved eyes, his protest continued in my brain:
“Look here, old sport, you’ve got to get somebody for me. You’ve got to try hard. I can’t go through this alone.”
In the end, only Gatsby's father and "Owl Eyes" show up for the funeral. What made this all the more difficult for Nick is that, in the public eye, Gatsby was blamed for Myrtle's death. As Gatsby spent his life trying to recreate a memory, Nick felt it was a travesty that he would be remembered poorly and/or, judging by the lack of attendees at his funeral, not remembered at all.