Please follow this blog to troubleshoot SQL connectivity issue and post question here.
Steps to troubleshoot SQL connectivity issues
Lot of blogs related to SQL connectivity issue are available sql_protocols blog.
http://blogs.msdn.com/sql_protocols
(Update: Please search your error message in this forum before you post your question, there are probably already answers in previous posts. If your scenario is different, please start a new thread rather than appending to old ones. Please reply this thread if this searching step solves your issue. We would like to hear from you. Thanks).