website is currently unable to handle this request" error?

Hi,

why am i getting this error:

The store-mahirehan.com page isn’t working
store-mahirehan.com is currently unable to handle this request.
HTTP ERROR 500

Does anybody have any idae what file is missing or what should be done in such situations?

Thank you

I suggest you get a developer who knows what they're doing to look at this to avoid any more data loss.