When first time I installed Zabbix Server (Installation of Zabbix Server on Linux), I need to login on Dashboard. but I don’t know Username/Password for same. Somehow i did Google and get to know default password for Zabbix Dashboard.
zabbix_logo
Default UserName and Password for Zabbix
UserName :- Admin
Password :- zabbix

But if you foget password and you dn’t have any other Admin account to login and configure Zabbix. In this small post I would how with very simpe command in Dtabase (MySQL), you could reset admin password
You just need to Login on MySQL from Linux command prompt through User that have full access on Zabbix database. All commands show below.

Through MySQL root User

# mysql -u root -p
Enter password:
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)
[root@srv3 ~]# mysql -u root -p
Enter password:
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 105
Server version: 5.1.71 Source distribution

Copyright (c) 2000, 2013, 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> update zabbix.users set passwd=md5('passw0rd') where alias='Admin';
Query OK, 0 rows affected (0.01 sec)
Rows matched: 1  Changed: 0  Warnings: 0

mysql> Bye

Through MySQL Zabbix User

# mysql -u zabbix -p
Enter password:
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 200
Server version: 5.1.71 Source distribution

Copyright (c) 2000, 2013, 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> update zabbix.users set passwd=md5('passw0rd') where alias='Admin';
Query OK, 0 rows affected (0.01 sec)
Rows matched: 1  Changed: 0  Warnings: 0

mysql> Bye