Arvind, both Jan and I told you your code has flaws. There was also comment about your comments. All you've managed to do is make your code more readable - but the code is still flawed. I mentioned about your loop control and some methods of debugging the code - but you give us comments. Even without the comments I told you I couldn't understand how the code was supposed to work, I still don't understand how it works even with the comments.

If you want a ready made solution, search this site and use Goggle - there's heaps of examples on doing matrix keyboards. Otherwise, apply some time and some logical thinking to your problem. In time you'll wonder why you didn't solve it earlier.