You can buy the parts on ebay it's about 60 bucks but make sure you get the both the glass+lcd frame. Once you have the part it's very simple to replace it.
Turn off phone
Turn it to its back n take off cover
Takes off any screws you see
Then you take your nails or guitar pick n in between the screen frame container and the body and go around till u get it off (u can tell where they are both separate) just be careful around the power and volume buttons. U don't want to rip those off
Once that's done take off the the big black ribbon and a small ribbon, so taking off two (if u look at your new part you can tell which ones are they)
Now you turn it over n heat that sucker up n use the same guitar pic to go around to take off the glass u Goin to have to do it over and over, then once that is off u take both the Glass n lcd out n put in the new one (there is a bottom ribbon sort of a tricky fellow but u must plug it in as well u will know when u see it).
Then heat the glass one more time so it can stick to he glue again. Put it back together and your good to go.