“There is no server on port 443” Error

I used to access sharepoint site using sharepoint designer till yesterday.
Yesterday all of a sudden I am not able to access it using sharepoint designer.
I can access it in browser. When try to open the site in sharepoint designer, It says,

There is no server on port 443 at ‘mysite.com’.
You have selected the Connect Using SSL option.
This connection problem may indicate that the server does not support Secure Socket Layer(SSL) communications, or that it uses SSL communications on a different port.

Now, is there a chance the site port has been changed? If yes, how can I change this port in Designer.