Search for the song on Midomi, an online music search engine that searches based on a recorded sample of the user singing or humming the song in question. Go to the Midomi website and click the "Sing or Hum" button at the top of the main page. Sing or hum at least 10 seconds or more of the tune's melody into the computer's microphone, then click the arrow button to view the search results.
Go to the Best Classical Tunes website and use their online tune lookup service to search for a tune by notes. Play the first 10 notes of the tune by clicking on the virtual piano. Click the "Look This Up" button below the virtual piano to search for the tune. View the results on the next screen, or go back and try playing the tune again if unsatisfied with the search results.
Search an online song lyrics database for some of the tune's memorable lyrics. Some online lyrics databases include Lyrster and eLyrics. If online lyrics databases prove ineffective in finding a particular tune, try entering some of the song's lyrics in quotation marks into a search engine like Google, Yahoo or Bing. Putting the lyrics in quotation marks forces the search engine to return only websites that have that exact phrase in their text, and helps narrow results.