I can not connect to the database Error 40

I can not connect to the database Error 40

TITLE: Connect to Server
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Can not connect to <localhostname>.

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ADDITIONAL INFORMATION:

Error related to the network or instance-specific while establishing a connection to SQL Server. Could not find server or it was not accessible. Verify that the instance name is correct and that SQL Server is configured to support remote connections. (provider: Named Pipes Provider, error: 40 - Could not open a connection to SQL Server) (Microsoft SQL Server, Error: 3)

For help, click: http://go.microsoft.com/fwlink?ProdName=Microsoft+SQL+Server&EvtSrc=MSSQLServer&EvtID=3&LinkId=20476

Try to localhost, "." but nothing works, I would like to help me