Hum the melody of the song that you are trying to find. Practice this until the melody is as accurate as possible.
Turn on your computer and open a web browser. Search Google or Yahoo! for "Midomi" or "Musipedia."
Visit either the Midomi or Musipedia website. On the Midomi website, you can sing or hum a song, and the service will attempt to recognize the melody and search its database of songs to provide you with the artist and the song title. On the Musipedia website, you can sing or whistle the melody you have in mind or use a virtual keyboard to play the melody. Once you have done this, Musipedia's Melodyhound search engine will attempt to locate the song to which the melody belongs.
Play each sample of the songs provided as results to your melody query populate in the Midomi or Musipedia search result. Determine which song is the one from which your melody comes. Take note of the song title and artist for future reference.