The W580i LCD is easy, easy to replace. Probably one of the easiest I have ever done.
Check out the following link for instructions on replacing the LCD display and links to buy the screen.
Sony W580i LCD Screen Replacement
I hope that helps you out
Bsnl - internet setting for k750i sonyericsson
i have internet in my pc then how to connent the interent to my mobile.
Check your carriers website, they usually post that info in the support area.