C:\Users\ your user name \ appdata \ local \ Google \ chrome \ userdata \ default \ cache

in it, the name is not MP3, and there should not be too many files in it. You should look for a file whose creation date is close to the time when you listened to the song, and the file is generally large, a few meters long. Copy it and add the suffix ..

windows 7 chrome browser

if you only have IE browser, you're too lazy to try.