A cracked screen indicates external damage to the camera (drops, etc), which are usually not covered under manufacturer warrantees... Those are designed to cover manufacturer defects or electrical issues, I'm afraid.
What kind of camera? Is the screen at all fictional, or totally unusable? If it just doesn't turn on, depending on the model you might be able to get away by using the EVF or adding on an EVF. It also might be worth looking into third-party camera repair; I took my GX1 to a reputable repair shop in NYC near B&H when I dropped it, and even though it ended up that the camera was totaled I appreciated their frank appraisal.
Either way, I'm sorry to hear about your screen. That sounds like a real bummer; good luck, I hope you can get it fixed!!