Cannot log in to my account

I put in my user name and password ( I know its correct) and it then says 'retreiving account information" and then it just goes back to the log in screen. this has been happennig to me for the past 3 days, i called comcast and they just said it must be my username and password. they suck, I have been using the same username and password for 5 years on this site. Its the website.