LIFE
Take inspiration from things that have happened in your life and those around you. Wether the memories are good or bad, try and remember how things made you feel. Or take things from how others have said they have felt and what they have done.
Take ideas from books, films etc, "Dont stand so close to me" by the Police is based on the idea of the story "Lolita" and the lyrics even mention "that book by Nebokov" (not sure how to spell the authors name).
Get a packet of Post-it notes and write a sentence, a favourite saying, a song title or line from a favourite song, a tv or film title, a line you overheard in the post office, a newspaper headline,something you saw on advertising hordings, even on the back of a bus.
Lyrics are all around you. When you have used a heck of a lot of notes, jumble them around, take a few at random. Stretch ideas, lyrics could come.
Just try to avoid lyrics like "Doo be doo be doo, I love you" that has been done far too many times.