History is full of colorful events that make great fare for songwriters. Find a historic event, whether it's something tragic or triumphant, and turn it into a song. Think of the event as a story. Learn as much as you can about the event, then encapsulate it into three or four verses, a couple of choruses and a bridge. Grab an acoustic guitar and strum some chords behind the lyrics as you write them, choosing a musical tone that fits the mood of whatever historic event you're writing about. Gordon Lightfoot did it with "The Wreck of the Edmund Fitzgerald."
Romantic ballads never go out of style. Go back to your first crush and think about those feelings. Although we've grown older and wiser since that time, those emotions are no less valid and will help you write lyrics that anybody who has ever had a crush or been in love can identify with. Within the scope of the romantic ballad, consider writing about the downside of love as well. Look for universal themes that music lovers will latch onto. Almost everyone has had a broken heart. Romantic ballads don't always need to have happy endings.
Songwriting is an effective medium for advocating change. If you have an opinion, don't be afraid to voice it through your songs. John Cougar Mellencamp has written songs about the plight of the farmer and racism and hatred. Bob Seger has written songs about the injustice of war. There's no law that says music can't be fun, danceable and have a political or social message.
There's nothing wrong with singing about good times with friends, running wild in the streets and being young. If you remember these things from your youth, or if you're still living them, share those feelings through your songs. Not every song has to be deep and meaningful, though those songs have more substance. Sometimes music is just about having fun. Share the joys of your youth with the young kids listening to music today. There's probably a lot more in common there than either side realizes.