From the Windows Start menu, click All Programs / Microsoft SQL Server 2017 / Configuration Tools / SQL Server 2017 Configuration Manager

1. Open up 'SQL Server Network Configuration' and click on 'Protocols for MSSQLSERVER':
   
2. On the right-hand side of the window, right-click on 'TCP/IP' and click Enable:
   
3. A message will show explaining the services need restarted. Close the message and on the left-hand side of the window, click on 'SQL Server Services':
   
4. On the right-hand side of the window, right-click on 'SQL Server (MSSQLSERVER)' and click Restart: