At the beginning of the song the speaker, addressing a lost love, recollects times that he and his lost love used to spend together, running down "The rainy roads of our old town." This is an example of pathetic fallacy, which is a technique whereby the weather is used to reflect the mood of the speaker or the mood of the story. The rain here reflects the sadness of the speaker, who is sad because he has lost contact with this person who he once loved, and perhaps still loves. The pathetic fallacy in this example is also emphasized by the alliteration of "rainy roads."
Throughout the song there are lots of examples of metaphors. For example, the speaker says to his lost love that he hopes that one day "You'll follow me back with the sun in your eyes." This is a metaphor because of course the speaker does not hope that the sun will somehow literally be in her eyes, but rather he hopes that her eyes will be bright and warm with the joy of seeing him once again. This metaphor also perhaps suggests that the moment when his lost love returns to him will represent a new beginning, just as a rising sun heralds a new day.
The speaker also uses a metaphor when he says to his lost love, "I know you think ... I've fallen by the wayside now." This metaphor implies that the speaker, from the perspective of his lost love, has become irrelevant and meaningless. The speaker is trying to imply that this is not true, and that he is still relevant, and that he still has meaning.