I'm sorry, I could not find the complete lyrics of "一路向北 C调转调（半音阶口琴）" by 方文山 in my web search results. The closest result I found was a video of a harmonica cover of the song by a user named "Harmonica King" on YouTube[^1^]. The video description says that the song is in C major and uses a chromatic harmonica. The user also provides a link to a PDF file with the harmonica tabs[^2^]. Maybe you can use that as a reference to play the song yourself. I hope this helps. ?

[^1^]: [一路向北 C调转调（半音阶口琴）](^1^)
[^2^]: [PDF file with harmonica tabs](^2^)