mysql Access denied for user 'root'@'%' 的解决

版本5.5.28
Stop your MySQL server completely. This can be done by accessing the Services window inside Windows XP and Windows Server 2003, where you can stop the MySQL service.
Open your MS-DOS command prompt using "cmd" inside the Run window. Inside it navigate to your MySQL bin folder, such as C:\MySQL\bin using the cd command.
Execute the following command in the command prompt: mysqld.exe -u root --skip-grant-tables
Leave the current MS-DOS command prompt as it is, and open a new MS-DOS command prompt window.
Navigate to your MySQL bin folder, such as C:\MySQL\bin using the cd command.
Enter mysql and press enter.
You should now have the MySQL command prompt working. Type use mysql; so that we switch to the "mysql" database.
Execute the following command to update the password:
UPDATE user SET Password = PASSWORD('NEW_PASSWORD') WHERE User = 'root';
ctrl+c 停止第一个窗口再退出第二个窗口，然后重新启动操作系统。