You updated your PHP version and the website is not working? Well this basically happens when you have an old website. Reverting back might help but if it’s a shared hosting and if other websites are working on the latest version of PHP you possibly would want to only downgrade the PHP version for a particular website. This tutorial will guide through how you can change the PHP version of a specific site modifying the .htaccess file.
You will also find some easy way to find more about your PHP.
Please not this tutorial is not about updating to the new PHP version. For this you can simple go to the cpanel, look for PHP Selector (or similiar) and you will find the option there – or you can also have a word with your Hosting provider they should also do it for you at no cost.