Most likely, physical damage like a cracked screen won't be covered under warranty. Most manufacturers won't cover it. That's not to say they won't repair the laptop, but they'll charge you for the cost of the screen (which is usually much higher than aftermarket) and hit you for an exorbant amount of labor. Your best bets are to...
1) Find a replacement screen on eBay and swap it yourself. This usually isn't all that hard, if you're handy with a screwdriver. Usually it just involves finding the correct replacement, removing the laptop's screen bezel, and swapping screens. Most screens have two cables that are both quick disconnects. Just patience, caution, and attention to detail is all that's required. Not rocket science. On a scale...