Issues with Appearance Sub-Menu

Hi there, 

I have the Appointment Theme on my Wordpress site but am having problems updating the front page. I have downloaded the latest version of WordPress and most functionality is fine. Apart from the Appearance sub-menu. It will let me into "Themes", "Customise", "Widgets" and "Editor" but not "Header" or "Background", which is where I need to go right now. When I click on it it gives me this message: 

"This page isn't working. is currently unable to handle this request. HTTP ERROR 500. Reload". 

I wrote to my hosting site (123-Reg) to report the problem but following a few back and fores, they suggest it may be a theme related issue and to see if you guys have a possible fix. Also, they ask what requirements the theme has so we can advise if these can be met on their platform.

Can you advise please?  


This discussion has been closed.