Cracked iphone 4 and now screen doesn't work?

My little brother had my phone and i didn't see. I was busy cleaning out my closet, and he was jumping on the bed and dropped on the floor, I went to check on it and it cracked and some of the glass was on the floor, I turn it on to see if the touch worked and it didn't. I can see everything fine, but i can't slide to unlock or slide up. How do i fix it. Or how much will it cost to fix the screen, My older brother said it would be around 20$ but i don't really believe it.

Listen to your brother. The reason it's not working is because you broke the digitizer and they usually will cost you maybe 20 bucks to buy a new one. Maybe a little more if you get it repared at a store.