Explanation/Reference:
To enable the TCP/IP network protocol
1. Start SQL Server Configuration Manager. Click Start, point to All Programs, and click Microsoft SQL Server. Click Configuration Tools, and then click SQL Server Configuration Manager.
2. In SQL Server Configuration Manager, in the console pane, expand SQL Server Network Configuration.
3. In the console pane, click Protocols for <instance_name>.
4. In the details pane, right-click TCP/IP, and then click Enable.
5. In the console pane, click SQL Server Services.
6. In the details pane, right-click SQL Server (<instance_name>), and then click Restart, to stop and restart the SQL Server service.
References: https://technet.microsoft.com/en-us/library/hh231672(v=sql.110).aspx