I want to backup my wordpress blog fully, means with all files and all database. So that there will be no chance of any kind of data loss in server failure or something else. But i don't know how to do this? Can anybody help me for the same ?
If you have a website only hosting WordPress, it's easy to backup everything from the control panel your hosting provider offers. If there is no control panel, backup the home directory and the database it's using... that should do it.
You can also create a full back-up of a WordPress installation + MySQL database using an auto script installer like Softaculous or Installatron.
I guess you are using cPanel. Use phpMyadmin to backup the database and save the .sql file And then using FileManager compress the folder which contain the wordpress files and the download the .zip file
Some hosting company make it in automatic for your convenience, others companies are cheaper and can't provide this service You need to do manually with an FTP program for WP files and folder and need to go on phpMyAdmin for backup and download your DB. It can takes a nice amount of time (wasted IMHO)
If you don't have cPanel but have ssh access, you can backup your database with "mysqldump" command and than copy created database file and directory where wordpress is installed. This can be make with "scp" command.