@ruthmouch Have you checked your settings? No idea why they might have changed but stragner things have happened... go to 'you'- 'your settings' -'notifications' and see what it's set for? :)
hi ruth, this happened to me a few weeks ago: turned out it was my server that was at fault. If you have more than one email address that uses a different server you could change your settings to the other address and see if that works - that would then let you know it's probably the server and not the site.
Just a thought :)