How can I change Magento admin password
For standard way, you can update your admin password from your Magento backend
System -> My Account
or
System -> Permissions -> Users
For some cases, if you cant access backend. You can update via mysql e.g via phpmyadmin
UPDATE admin_user SET password=CONCAT(MD5('newpass'), ':sG') WHERE username='AdminUsername';“newpass” should be your new Magento admin password
“AdminUsername” should be your Magento admin username