Iphone 3gs Dead spot/ Unresponsive part on screen

Hello people,

I need to get some advise.
I have an iPhone 3gs 16gb, i am suffering months from so called dead spots, so that means i can touch the letter "P" or something that is on the same side.
I was really stupid and my iphone fell on the ground and i have a little crack on my screen, but everything is working fine only the deadspot is unresponsive.
My question is will i get an replacement for free for this dead spot if i make an appointement with a Genius? If not what is the problem behind this dead spot?er

(i have already read other topics, but none were giving clear information)

Greetings!

Need help ASAP