Here's a link to a good instructional video on how to play "Yesterday" by the Beatles.

"Yesterday" by Paul MacCartney

"Yesterday" by Paul McCartney

Lyrics

Yesterday, all my troubles seemed so far away

now it looks as though they're here to stay

Oh, I believe in yesterday

This is the context of the speaker. Things used to be good

Now they are bad

Now he is longing for the past. Longing for the good times spoken of in line 1.

Suddenly, I'm not half the man I used to be

There's a shadow hanging over me

Oh yesterday came suddenly

further description of the bad without full disclosure

the next line remains on the point of his pain.

the unexpected nature of the bad makes us feel sorry for the speaker and identify with him.

Why she had to go I don't know she wouldn't say

Here's the full disclosure of the bad. But the speaker does not say, "My love left me." The speaker assumes we know already, and we are allowed to ascertain the situation from this one statement.

I said something wrong now I long for yesterday

This line evokes sadness because of the blame that the speaker puts on himself. We also infer that he said something wrong on accident. "...now I long for yesterday," is the sum of what the speaker is feeling. It's the most straight ahead statement in the whole song, but it only hits us powerfully because of what we know or think we know about the bad situation.

Yesterday, love was such an easy game to play

now I need a place to hide away

Oh, I believe in yesterday

The first line uses the game metaphor, and the second line talks about hiding away. The connection is the childishness of games and then the terror of the new found darkness in a once bright world.

Why she had to go I don't know she wouldn't say

I said something wrong

now I long for yesterday

Because of the half verse, the return of "Why she had to go..." is not completely expected. It retains a degree of freshness.

yesterday, love was such an easy game to play

now I need a place to hide away

Oh, I believe in yesterday

I can't think of why the first verse wasn't used here to conclude the song except that these lines have the word "love" in them and that helps us remember that this is a love song, but no matter what set of lines return here, the repetition of something we've heard already gives a sense of conclusion.

These lyrics don't spell out very much. The main focus in the verses is on the state in which the speaker finds himself. Left alone, bewildered, and longing for what he just lost.

The first verse states the situation in general terms of good and bad. The second verse continues to describe what the bad situation is like. It doesn't describe the bad situation in terms of facts; it describes the situation in terms of how bad it is. The third verse exhibits the same structure as the first verse in that it describes what was good and what has now turned to bad. It accomplishes almost exactly what the first verse accomplishes but with different words. This is an important point because it shows that you don't need a lot of ideas to write multiple verses. Try saying the same thing twice but with different words, and you may find that you have created verse one and verse two.

The chorus is where the facts are conveyed in this song, but they are far from simply factual statements. "Why she had to go..." sounds like something a person going through great pain would say in the midst of that pain. This and the line that follows are words that are in character with the speaker. They are not just explanatory, although, from them, the listener can infer some kind of a scenario.

Melody

The main issue I want to point out about this melody is it's relatively long form. Each verse is a melody with a beginning and an end. Many modern pop song verses are made up of one or two short melodic lines that are repeated a couple times, but "Yesterday" contains a seven bar, verse melody. It starts with that one note annunciation of "Yesterday..." then continues to grow into a rising line that breaths for a moment, then slowly moves downward, breaths again, and ends with a circular D minor arpeggio before it resolves on the third scale degree.

This kind of long melody is more commonly found in popular songs from the earlier twentieth century by composers such as George and Ira Gershwin, Kurt Weil, and Irving Berlin. Melodies like "Yesterday" and ones written by American Songbook composers usually have some memorable moment that makes them classics instead of a single line that's gets repeated over and over.

One way of explaining the odd, seven bar verse is by dividing it up into phrases. With the first bar as it's own phrase, the rest of the verse can be divided into three two-bar phrases. If the one bar phrase fell at the end of the seven bar pattern, the oddness might be felt because the last phrase might feel short-shrifted. With the odd bar at the front of the verse, it can gel it's way into the next phrase without any abruptness being felt. What also helps the gelling is for there to be so much space between "Yesterday" and "all my troubles seemed so far away."

As for the chorus, note that it begins on a transition chord and resolves on the lyric "something." Most choruses are setup by a transition chord and then the chorus lyrics starts on the resolution. Both are strong moves, but singing over the transition in this case makes for an organic transition. The melody here is enforced by repetition, which distinguishes it as more important than the verse melody.