Have you edited the public page templates at all to change them from default? Are you running the latest version of phpList from the Automatic Updater / Sourceforge?
There were some jQuery related issues some months ago which caused public pages to be blank but they were resolved a few releases back. If you inspect the page source code and find that the HTML body tag has a CSS class which makes it invisible, then it’s jQuery related.
@rgjerde Your change isn’t actually correct but might not matter. A mistake was introduced earlier this year in this change that assumes the php version is at least 5.4 (which supports the [0, 1] short array syntax).
But you should really be running an up to date version of php, yours is years out of date, is no longer supported and probably has security issues.