Replacement of screen

hey friend. i accidently cracked my imate's screen by dropping it .i would like to know how much will it cost me if i got it fixed by a tecnician . . . or if you live in pakistan , how much will unitedmobile cost me if i got it fixed ?????

and in case i can't get a technician i have a request... please forward me the document which will guide me on how to replace my cell's screen ... i will be thankfulll 2 u ....