Solution :
Stop your MySQL service
/etc/init.d/mysqld
stop (UNIX style)
Start your MySQL with privileges
/usr/bin/mysqld_safe –skip-grant-tables
Connect to mysql DB with your root user /usr/bin/mysql -uroot -p mysql
Update root privileges
update user set Select_priv=’Y’, Insert_priv=’Y’,Update_priv=’Y’,Delete_priv=’Y’, Create_priv=’Y’,Drop_priv=’Y’,Reload_priv=’Y’,Shutdown_priv=’Y’, Process_priv=’Y’,File_priv=’Y’,Grant_priv=’Y’,References_priv=’Y’, Index_priv=’Y’,Alter_priv=’Y’,Show_db_priv=’Y’,Super_priv=’Y’, Create_tmp_table_priv=’Y’,Lock_tables_priv=’Y’,Execute_priv=’Y’, Repl_slave_priv=’Y’,Repl_client_priv=’Y’,Create_view_priv=’Y’, Show_view_priv=’Y’,Create_routine_priv=’Y’,Alter_routine_priv=’Y’, Create_user_priv=’Y’,Event_priv=’Y’,Trigger_priv=’Y’ where User=’root’;
After that, you just need to stop the MySQL service and start again.