先给大家介绍windows下mysql忘记密码的解决方案。
Windows下的实际操作如下
1.关闭正在运行的MySQL。
2.打开DOS窗口,转到mysqlbin目录。
3.输入mysqld --skip-grant-tables回车。如果没有出现提示信息,那就对了。
4.再开一个DOS窗口(因为刚才那个DOS窗口已经不能动了),转到mysqlbin目录。
5.输入mysql回车,如果成功,将出现MySQL提示符 >
6. 连接权限数据库>use mysql; (>是本来就有的提示符,别忘了最后的分号)
6.改密码:> update user set password=password("520") where user="root"; (别忘了最后的分号)
7.刷新权限(必须的步骤)>flush privileges;
8.退出 > q
9.注销系统,再进入,开MySQL,使用用户名root和刚才设置的新密码123456登陆。
第一步
  C:Documents and SettingsAdministrator>cd D:webwww.php100.comMysqlMySQL Se
  rver5.5bin
  C:Documents and SettingsAdministrator>d:
  D:webwww.php100.comMysqlMySQL Server5.5bin>mysqld --skip-grant-tables
第二步
  Microsoft Windows [版本 5.2.3790]
  (C) 版权所有 1985-2003 Microsoft Corp.
  C:Documents and SettingsAdministrator>cd D:webwww.php100.comMysqlMySQL Se
  rver5.5bin
  C:Documents and SettingsAdministrator>d:
  D:webwww.php100.comMysqlMySQL Server5.5bin>mysql
  Welcome to the MySQL monitor. Commands end with ; or g.
  Your MySQL connection id is 1
  Server version: 5.5.10 MySQL Community Server (GPL)
  Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved.
  Oracle is a registered trademark of Oracle Corporation and/or its
  affiliates. Other names may be trademarks of their respective
  owners.
  Type 'help;' or 'h' for help. Type 'c' to clear the current input statement.
  mysql> use mysql;
  Database changed
  mysql> update user set password=password("520") where user="root";
  Query OK, 1 row affected (0.00 sec)
  Rows matched: 1 Changed: 1 Warnings: 0
  mysql> flush privileges;
  Query OK, 0 rows affected (0.00 sec)
  mysql> q
  Bye
  D:webwww.php100.comMysqlMySQL Server5.5bin>
下面给大家介绍linux下mysql的root密码忘记解决方案
1.首先确认服务器出于安全的状态,也就是没有人能够任意地连接MySQL数据库。 
因为在重新设置MySQL的root密码的期间,MySQL数据库完全出于没有密码保护的状态下,其他的用户也可以任意地登录和修改MySQL的信息。可以采用将MySQL对外的端口封闭,并且停止Apache以及所有的用户进程的方法实现服务器的准安全状态。最安全的状态是到服务器的Console上面操作,并且拔掉网线。 
2.修改MySQL的登录设置: 
# vi /etc/my.cnf 
在[mysqld]的段中加上一句:skip-grant-tables 
例如: 
[mysqld] 
datadir=/var/lib/mysql 
socket=/var/lib/mysql/mysql.sock 
skip-grant-tables 
保存并且退出vi。 
3.重新启动mysqld 
# /etc/init.d/mysqld restart 
Stopping MySQL: [ OK ] 
Starting MySQL: [ OK ] 
4.登录并修改MySQL的root密码 
# /usr/bin/mysql 
Welcome to the MySQL monitor. Commands end with ; or g. 
Your MySQL connection id is 3 to server version: 3.23.56 
Type 'help;' or 'h' for help. Type 'c' to clear the buffer. 
mysql> USE mysql ; 
Reading table information for completion of table and column names 
You can turn off this feature to get a quicker startup with -A 
Database changed 
mysql> UPDATE user SET Password = password ( 'new-password' ) WHERE User = 'root' ; 
Query OK, 0 rows affected (0.00 sec) 
Rows matched: 2 Changed: 0 Warnings: 0 
mysql> flush privileges ; 
Query OK, 0 rows affected (0.01 sec) 
mysql> quit 
Bye 
5.将MySQL的登录设置修改回来 
# vi /etc/my.cnf 
将刚才在[mysqld]的段中加上的skip-grant-tables删除 
保存并且退出vi。 
6.重新启动mysqld 
# /etc/init.d/mysqld restart 
Stopping MySQL: [ OK ] 
Starting MySQL: [ OK ]