By default, mysqld produces error messages in English, but they can also be displayed in any of these other languages: Czech, Danish, Dutch, Estonian, French, German, Greek, Hungarian, Italian, Japanese, Korean, Norwegian, Norwegian-ny, Polish, Portuguese, Romanian, Russian, Slovak, Spanish, or Swedish.
To start mysqld with a particular language
for error messages, use the --language or
-L option. The option value can be a language
name or the full path to the error message file. For example:
shell> mysqld --language=swedish
Or:
shell> mysqld --language=/usr/local/share/swedish
The language name should be specified in lowercase.
By default, the language files are located in the
share/
directory under the MySQL base directory.
LANGUAGE
You can also change the content of the error messages produced by the server. Details can be found in the MySQL Internals manual, available at http://dev.mysql.com/doc/. If you upgrade to a newer version of MySQL after changing the error messages, remember to repeat your changes after the upgrade.

User Comments
If you want to change the default language for the MySQL Administrator edit the my.ini that stored the options for mysql server and type the full path of your language e.g:
c:/mysql/share/spanish/ in fact c:\mysql\share\spanish\
almost the service was started without problem using the first option.
hope this help !!!
Happy Hollidays 4 All
Add your own comment.