error after installing jetpack

Depending on your plugin settings, that could indeed be the cause. It could also be linked to your server configuration.

Is your website 2lions.tk? If so, you can see the problem by yourself by trying to access your site’s XML-RPC in your browser:
http://2lions.tk/xmlrpc.php

This file should be accessible and will normally display the following message on a single line:
XML-RPC server accepts POST requests only.

On your site, I get a 410 error when trying to access the file:
http://i.wpne.ws/h7YR

$ curl -A "Jetpack by WordPress.com" -is -H 'Content-Type: text/xml' --data '<?xml version="1.0"?><methodCall><methodName>demo.sayHello</methodName><params></params></methodCall>' 'http://2lions.tk/xmlrpc.php' && echo
HTTP/1.1 410 Gone
Date: Thu, 18 Aug 2016 11:06:06 GMT
Server: Apache
Content-Length: 1
Content-Type: text/html; charset=iso-8859-1

This could be caused by your plugin, by another security plugin on your site, or your hosting provider may be blocking access to the file. If deactivating security plugins doesn’t help, I’d recommend getting in touch with your hosting provider to let them know about the issue.

Here is an example of the expected output that you can send them:
https://ww.wp.xz.cn/xmlrpc.php

I hope this helps.