Sometimes, depending on the server’s configuration in the event of an error where the server doesn’t know what to do with some code you’ll get either a blank page or a 500 error reported by the server.
A 500 error generally means that the server was asked to do something that it can’t do, be that because of a bug or because it’s specifically denied. You need to see if this issue occurred after you made a change. If it did, then try to undo the change and see if the problem goes away. If it’s just occurred without you doing anything, then it’s possible that your hosts have changed something on the server which has triggered the issue.
As 500 errors are non-specific (for security reasons) without further information we cannot diagnose it. If you’ve undone any changes that you may have done to trigger the problem and it remains then you’ll need to contact your hosts and ask them for the PHP error log (not the Apache or Jomres error logs, they are different logs). It is possible that you already have access to these logs via your hosting service’s control panel but if you do not (and some hosts don’t offer them) then you’ll need to contact them directly either via phone or email or their ticket system for the logs.
Remember, without these logs we cannot diagnose the issue further as we’ve got no information to work from to determine what the issue is.
