You want to block access of your site from particular IP Address, use the following tips!!!. Create a .htaccess file to your root folder and add the lines, replace xxx.xxx.xxx.xxx with IP address. You can add more than one IP by repeating the same line (deny from) with each IP Address.
The .htaccess
order allow,deny allow from all deny from xxx.xxx.xxx.xxx deny from xxx.xxx.xxx.xxx
Have fun!! 
