Comments not working

Hi,
I am unsure if this is the right place to post, but I wondered if someone could help.

There is no way to comment on my blog posts anymore, i.e. people can still fill in the comment, but when they try to post it takes them to a page that says

The requested page has not been found

I have been googling the issue for hours but cannot seem to find anyone with a similar problem.

My website is: http://melaniemartinphotography.co.uk