I followed one tutorial on how to connect to Mysql database. It connected to db4free.net , But its refusing to connect to localhost.
Needed Help... enter image description here
What you are doing is, that you try to connect to the localhost on your phone. And there won't be any instance of MySql. A better and more recommended way is to abstract the database behind a webservice. Than you can easily communicate with that service inside your app.
Please read the Xamarin guide about webservices for further information on that topic.