Task Manager
View | Select Columns | Check PID | OK
Find sqlservr.exe as the Image Name, note the PID
Command prompt:
netstat -ano | findstr *PID*
The PID is displayed in the far right. Look for the TCP entry. The port will be after the colon (e.g. 0.0.0.0:1433 means the port is 1433).”
Source: http://sqlserverpedia.com/blog/sql-server-bloggers/what-tcp-port-is-sql-server-running-under/