Write down the song lyrics or as many as you can remember as soon as possible. This will prevent you from forgetting the lyrics when the time comes to search for them.
Try to write down the chorus, as it is often repeated. The more lyrics you remember, the easier it will be to find the song. Sometimes lyrics can be difficult to interpret. If you do not understand all of the words, write down the ones you do know.
Open up a search page such as Google, Yahoo or Bing.
Type in the lyrics you remember into the search bar. Put quotation marks around the lyrics. Include the artist if you know him since it will help narrow down the song lyrics.
Look at the results. The title of the song should be in the web page title.
Call a friend and sing a portion of the song to her if you do not have access to the Internet. If the song is popular enough, your friend may know it.
If you know the artist but not the song title, locate and post a message on the forum of that artist's message board. It is very likely a fan will respond soon and tell you which song you are thinking about.