If your SQL Server isn't starting, check both Windows event log and the SQL Server error log. The SQL Server error log can be found in the
LOG
folder of your SQL Server instance (for example C:\Program Files\Microsoft SQL Server\MSSQL...\MSSQL\Log). Open the ERRORLOG file in notepad and search for errors preventing the startup.
If the SQL Server is running fine but you cannot connect to it, refer to for example
http://www.databasejournal.com/sqletc/article.php/1569851/Solving-SQL-Server-Connection-Problems.htm[
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