I found that after a routine cron based automatic update of webmin, a newly created site couldnt load php. I found that it was due to php version 7. Apparently it was broken.
To change php version for new sites:
Virtualmin > System settings > Server templates > Default settings > Edit template section > Apache website > Default PHP version
To change for an individual server:
Virtualmin > Server configuration > PHP versions
If you get a message stating “This virtual server is using the mod_php execution mode for PHP, such does not allow per-directory version selection.”: