Just curious, did your site have a mobile version pkKumar? My site has had a mobile version for a couple of years without problem but, as of this week, the Google preview is showing the desktop version where mobile used to be. Nothing has changed on my site and I'm seeing the same thing you are.
Check the total number of "not selected" pages in GWT, mine just spiked by a factor of 2x the number of pages on my site. Excuse me while I go remove the mobile version.