4♦ Four of Diamonds in The Rock Songwriter’s Deck: 52 Ways to Write a Song
The Four of Diamonds suggests a roundabout method for creating a new song. First, find a lyric sheet for a song you don't know. (Hint: You can do a Google search for some random combination of words, plus the word "lyrics.")
Write music for those lyrics, trying your best to guess what the original songwriter had in mind. When you're done, listen to the original song if you can. You'll probably be surprised at how different your treatment is from the song's original music. Most likely, you chose a different musical style, a different tempo, a different rhythmic structure, and different kinds of chords. (But if your music somehow ends up similar to the first songwriter's treatment, then you must throw your work out and start over with a different set of lyrics.)
Now you have just one little problem: your new song has lyrics whose copyright is owned by someone else. No sweat! Just write all-new lyrics for your new music.