I have updated and add repositories to sourcelist , but still doesn't work.
cyan@cyanonvo:~$ sudo apt install phpmyadmin [sudo] password for cyan: Reading package lists... Done Building dependency tree Reading state information... Done Package phpmyadmin is not available, but is referred to by another package. This may mean that the package is missing, it has been obsoleted, or is only available from another source. Package 'phpmyadmin' has no installation candidate cyan@cyanonvo:~$