I found out the styles are not getting applied because of Doctype defination error in dreamweaver. The present Doctype defination reads as follows;
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
The previous one was as follows;
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
I compared this difference this morning when I was working on dreamweaver at my office computer. Back home I changed back to my previous docktype defination and applied styles. Now everything working fine. But one thing...How this change has been taken place?...I think due to some malicious script intervention the change has taken place of its own. I want to get back to my previous dock type defination to be appeared in dreamweaver working page. Can you through some light where can I change the code so that every time I open the dreamweaver the previous code will appear.