In case you haven’t taken the time to set up a backup solution for your website, you definitely should. Having a recent backup can (and probably will) save you a giant headache at some point when you do run into a site breaking error.
We will perform series of checks to get rid of the issues.
You will need to change "public" folder permissions to 755 and "public/index.php" file permissions to 644 via FTP client or file manager.
Sometimes default .htaccess file in the main directory and/or "public" sub-folder might get overwritten by your server or not be uploaded at all. You will need to manually open these files and compare and verify that their contents match with the package downloaded.
Another reason could be that Apache mod_rewrite module might be disabled on your server/hosting. You will need to enable that module in order to fix this issue. It can usually be enabled from cPanel, but you might need to contact your hosting support and ask them to enable it for you.
If solutions above don't fix the issue, you can open "errors" page in your cPanel to get more information on what is causing that issue. If creating a new ticket regarding this, make sure you include that error log along with the ticket.
