Lost my PBX admin´s password, what can I do?

How can I get a new passwrod or enter from other side to reconfig that?

then ssh in with your root password and use either mysql as root to change the GUI password (if you are using the database authentication) or use httpasswd to generate a new one for that directory if you’re using httpd access control.

If you are talking about freePBX GUI access…

In /etc/amportal.conf change:
AUTHTPE=database to AUTHTYPE=none and restart asterisk

Than change your admin user password and reverse the process…