this issue sometime occurs when you tried to change password while you are setting up database and openfire server.
To avoid this issue do one thing first clear your db and again generate new one it will create one admin user under ofuser table.
After doing this you need to set false under tag in openfire.xml which is live under installation-dir/conf/openfire.xml.
again setup server with newly created db and then don’t change your password and after finishing setup launch admin and then login with username-admin and password will be admin. if it still shows wring username-password then try after restarting server.