Upgrade php to 5.6 or higher

My php is 5.6 only and my hosting has no option for higher version

do i need to change php extentions?

and now when i m tring reinstalling the plugin this is the error.

Sagar, as to the last error on plugin reinstall, you need to enable openssl extension in your php.ini and restart the server. As to the issues with the plugin, create a post in the plugin support area or contact plugin developer directly as we do not provide assistance with 3rd party items issues. 

for plugin installation. why do I need to change php.ini? earlier it was working properly. and now I could not install any plugin.

Because it is our server requirement, please check: http://www.oxwall.org/hosting

Did you try to use some another proxy? Maybe it can help to fix the issue. Something like http://advanced.name, or other?