WordPress v4.0 and above.
- Change the language in the admin settings screen by navigating to Settings > General > Site Language.
WordPress v3.9.2 and below
After translating successfully a theme, we need to tell WordPress which language you want to use. So you need to make sure that your wp-config.php matches your language files.
For example, if your language is French, you change the following code line in the wp-config.php file:
define ('WPLANG', '');
define ('WPLANG', 'fr_FR');
Save all changes and enjoy!