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Confirm the instance of the SQL Server Database Engine is installed and running.
Logon to the computer hosting the instance of SQL Server.
Start SQL Server Configuration Manager. (Configuration Manager is automatically installed on the computer when SQL Server is installed. Instructions on starting Configuration Manager vary slightly by version of SQL Server and Windows. For help starting Configuration Manager, see SQL Server Configuration Manager.)
Using Configuration Manager, in the left pane select SQL Server Services. In the right-pane confirm that the instance of the Database Engine is present and running. An instance named SQL Server (MSSQLSERVER) is a default (unnamed) instance. There can only be one default instance. Other (named) instances will have their names listed between the parentheses. SQL Server Express uses the name SQL Server (SQLEXPRESS) as the instance name unless someone named it something else during installation. Make a note of the name of the instance that you are trying to connect to. Also, confirm that the instance is running, by looking for the green arrow. If the instance has a red square, right-click the instance and then click Start. It should turn green.
If you are attempting to connect to a named instance, make sure the SQL Server Browser service is running.
Get the IP Address of the computer.
On the Start menu, click Run. In the Run window type cmd, and then click OK.
In the command prompt window, type ipconfig and then press enter. Make a note of the IPv4 Address and the IPv6 Address. (SQL Server can connect using the older IP version 4 protocol or the newer IP version 6 protocol. Your network could allow either or both. Most people start by troubleshooting the IPv4 address. It's shorter and easier to type.)
Get the TCP port number used by SQL Server. In most cases you are connecting to the Database Engine from another computer using the TCP protocol.
Using SQL Server Management Studio on the computer running SQL Server, connect to the instance of SQL Server. In Object Explorer, expand Management, expand SQL Server Logs, and then double-click the current log.
In the Log Viewer, click the Filter button on the toolbar. In the Message contains text box, type server is listening on, click Apply filter, and then click OK.
A message similar to Server is listening on [ 'any' <ipv4> 1433] should be listed. This message indicates that this instance of SQL Server is listening on all the IP addresses on this computer (for IP version 4) and is listening to TCP port 1433. (TCP port 1433 is usually the port used by the Database Engine. Only one instance of SQL Server can use a port, so if there is more than one instance of SQL Server installed, some instances must use other port numbers.) Make a note of the port number used by the instance of SQL Server that you are trying to connect to.
