To turn on error reporting on your Joomla website, simply:

1. Navigate to the admin area of your website and login
2. Navigate to the Global Configuration
3. and click on the Server tab option

From here you will see the screen with "server setting" options.

For the option, "Error Reporting", try setting this to simple at first.

This will alert you of any serious malfunctions on the website. If that doesn't work then up the level of reporting step by step until maximum.

Please note that maximum will show you everything including notifications and warnings on your website. These would be very numerous.