Open the SQL Server Configuration Manager:
The following Window will be presented:
Click on SQL Server Services in the left pane. Then, double-click on SQL Server Browser in the right pane.
Click on the Service tab and then make sure the Start Mode is set to Automatic.
After the Stat Mode has been set, click on the Log On tab.
Click on Start to start the Browser Service.
Next, in the SQL Server Configuration Manager, click on SQL Server Network Configuration, and then the Protocols for XXXXXX. (XXXXX is your instance name, usually SQLExpress).
If TCP/IP in the right pane shows Disabled, right-click on TCP/IP and select Enabled.
Restart the SQL Server Service by right-clicking on SQL Server XXXXX in the right pane and selecting Restart.