Did both you and your client sign a contract before you started the project? If so look through that contract and look for any clauses related to communication and lack of, I usually make sure my contract states failure of communication from the client side would mean I will be able to invoice them for the time I've spent on their project.
Have you tried calling them instead of email?
Personally I'd do all I can to get paid for at least the time spent on the project but if there's a written contract involved I'd have a good look at it and see if I could get it all.
