Cracked my iPhone 6. Will I have to pay out?

So IIm with sprint and they have that weird phone plan where you get the phone for free and pay month to month and if, at the end of your contract you decided to keep it, you pay the rest upfront or you can give it back no charge. Well my contract is up and has been for over a month, but I dropped my phone (literally fell off my lap and hit the ground. A foot drop MAYBE. This happened maybe 2 weeks before my plan was up so I so mad) and the screen shattered. I had an expensive case on it, but obviously it was a waste of money. My question is: will I have to buy the phone because it's damaged or will sprint still take it back? I didn't get insurance in the phone. And I definitely don't want to keep it (even if it wasn't broken). If I have to pay it i'm going to buy a screen replacement kit because HELL NAH with paying $400+ to buy the phone. So what happens now?

Company ought to have terms and conditions which will tell you what happens if a phone is damaged. I'd look that up.