can't open websites manager

All of a sudden I am getting a message 

404 - File or directory not found.

The resource you are looking for might have been removed, had its name changed, or is temporarily unavailable.

I could get on at 3 PM today, but not at 9 PM.   Did you change something?  I was told with Constant Contact that it could be Avast and I have disabled Avast,  but still getting this message.