How does Fitzgerald portray drunkeness in the end of chapter 2 of "The Great Gatsby"? having trouble getting started with this question...if anyone...

Pay attention to shifts in time, gaps in narrative, and Fitzgerald's use of descriptive language in this chapter.

Here are a few examples to help you get started:

Earlier in the chapter we are made aware of the way time is progressing strangely, and of a certain haze and fog that hangs over Nick's perspective of the party: "It was nine o'clock--almost immediately afterward I looked at my watch and found it was ten."  Later, Nick notes how people "disappeared, reappeared, made plans to go somewhere, and then lost each other, found each other a few feet away."  These kinds of passages set up the confusion and haze with which a drunken Nick views the proceedings.

The very end of the chapter really highlights these gaps and bits of missing knowledge.  I usually call this the "dot dot dot" incident.  Nick's narrative jumps suddenly from a conversation with Mr. McKee in the elevator to Nick standing beside Mr. McKee's bed.  How he got from point A to point B is narrated only with an ellipsis ("..."). The narrative shifts suddenly again, moving from Mr. McKee's bedside to the lower level of Pennsylvania Station. 

These gaps in the story augment the description of fogginess and time shifts set up earlier in the chapter when Nick was still at the party.  What indeed happens in the "..."?  Nick either can't or won't tell us.