听起来你的配置好像有问题，下面是一些你可以检查的东西:

Make sure that PHP is installed and running correctly. This may sound silly, but you never know. An easy way to check is to run php -v from a command line and see if returns version information or any errors. Make sure that the PHP module is listed and uncommented inside of your Apache's httpd.conf This should be something like LoadModule php5_module "c:/php/php5apache2_2.dll" in the file. Search for LoadModule php, and make sure that there is no comment (;) in front of it. Make sure that Apache's httpd.conf file has the PHP MIME type in it. This should be something like AddType application/x-httpd-php .php. This tells Apache to run .php files as PHP. Search for AddType, and then make sure there is an entry for PHP, and that it is uncommented. Make sure your file has the .php extension on it, or whichever extension specified in the MIME definition in point #3, otherwise it will not be executed as PHP. Make sure you are not using short tags in the PHP file (<?), these are not enabled on all servers by default and their use is discouraged. Use <?php instead (or enable short tags in your php.ini with short_open_tag=On if you have code that relies on them). Make sure you are accessing your file over your webserver using an URL like http://localhost/file.php not via local file access file://localhost/www/file.php

最后，查看PHP手册以获得更多的设置技巧。

我发现了另一个导致这个问题的问题，并且已经解决了它。我不小心将脚本保存为UTF-16编码。PHP5似乎不能识别<?PHP标签默认为16位编码。

php7.3。你可以尝试安装这些模块。这对我很管用。

sudo apt-get install libapache2-mod-php7.3

sudo service apache2 restart

今天，PHP自带一个内置的web服务器，所以不需要进一步的安装，因此呈现PHP文件用于开发使用的最简单的方法之一是:

打开一个终端，切换到包含web应用程序的源目录(它的主文件通常称为index.php)。 在这个目录中，键入php -S localhost:7777(端口号是任意选择的)。 打开web浏览器，在地址栏中输入localhost:7777，就会呈现所需的网页。

如果您已经完成了访问，那么返回您的终端并按CTRL-C关闭开发服务器。

这个信息也是通过在终端中调用php——help来给出的，进一步的信息在https://www.php.net/manual/en/features.commandline.webserver.php中给出

重新安装mcrypt模块对我有用。

$sudo apt-get install php5-mcrypt
$sudo php5enmod mcrypt

我有一个案例，我不小心开始解压我的文件目录在根。它从我的文件文件夹中添加了。htaccess文件，这将阻止所有php

# If we know how to do it safely, disable the PHP engine entirely.
<IfModule mod_php5.c>
  php_flag engine off
</IfModule>

底线检查根目录下的.htaccess文件。