The digitizer connector has probaly become dislodged slightly I have fixed many by opening the back and reseating the digitgizer cable. This is much more common when someone has removed the emi shield from the back of the board.
"Yup, you just need the digitizer. The LCD and digi come as one part so it should be an easy fix. If your not sure how to see youtube or get a pro to do it. You can buy the part here on this site or try other sites like;
"i dropped my iPhone 4, it fell, the fall formation preceded by the lower part and its near the iPhone speaker and the bottom part of the screen does not work and this is the only part that is not working
can you give me some tips to fix my phone with that problem of it."
