Hello Hareesh,
We have old instruction right now: http://www.flynax.com/forum/showthre...ersion-Upgrade
But if you have any customizations we do not recommend upgrade your site yourself because you lose your customizations and we cannot give you guarantee that your site will work properly.
Also from version 4.4 we removed mobile version because all our templates working with all devices. Responsive templates working properly like with desktop and with tablet and mobile devices. And we decided remove mobile version like additional functional.