MSSQLSERVER service does *not* start, port 1433 in use Sorry to raise if this has been asked before.
The SQL Server service is defined as manual, whenever I start it I get (event viewer):

Server TCP provider failed to listen on [ 'any'  1433]. Tcp port is already in use.
The SQL Server (MSSQLSERVER) service terminated with service-specific error
Only one usage of each socket address (protocol/network address/port) is normally permitted.

Odd thing both my ethernet and WiFi adapters have ipv6 disabled and it has ran fine for ages.
Environment details:

Windows 2008-R2;
SQL Server 2012 BI SP1;
all MSFT patches applied.
Find out what process is already using TCP 1433.  You can do this through the use of TCPView.  That utility is a sysinternals tool that gives you the information you need.  Just start it, pause the data view, and look at which process is using the local port of 1433 with the TCP protocol.

Note: You'll probably want to uncheck "Resolve Addresses" in the Options menu item so that you will be able to see the default instance port number.

Then once you know the process that is already using that port, you can take the appropriate action or reach out to the appropriate personnel that may know more about the process, why it's there, etc.

Or you could always change the port in which your SQL Server instance is listening on, but I'd personally be extremely curious as to which process is already using that port.