My iPhone screen went black but it's still on??

Everything was fine but then an app crashed and my screen went black; however, I can still use Siri and it still vibrates when it charges, although nothing shows up on the screen. I can't connect to iTunes on my computer and I've tried pressing the sleep/wake button, the home button, sleep/wake button + home button for 10 seconds, and nothing has worked!! :/ I cracked my screen a few days ago but I'm pretty sure it had something to do with the app crashing. What do I do?? Can I get it back??? Thanks!