Have you checked that a firewall or security software update hasn't started blocking your publishing?
Also, port 80 is used for http publishing (FrontPage Server Extensions) not for FTP publishing which uses port 21.
If you are publishing by ftp toggle over to active mode. Some web hosts require active mode for publishing but sometimes ISP (your home internet provider) might block active ftp on their side just like many of them block port 25 smtp so you can't send mail except through their mail servers.
Cheryl D Wise MS MVP Expression Instructor: starttoweb.com