WordPress it is widely used because is a free software. There are a lot of tweaks and one of these is to replace content in your wp database without using plugins .
So do to replace content in your WordPress database you have to login to your server and go phpMyAdmin .
After logging into phpMyAdmin, go to Run SQL interface and type the following
UPDATE wp_posts SET post_content = REPLACE ( post_content, ‘WORD1’, ‘WORD2’ );
In this example the WORD1 is replaced by WORD2 .
You can use this method to replace for example the name of you website :
UPDATE wp_posts SET post_content = REPLACE ( post_content, ‘SITE.COM’, ‘SITE.NET’ );
In this example the SITE.COM is replaced by SITE.NET .
Good luck !