Problem:  A Microsoft SQL instance cannot be access remotely through ODBC, Visual Studio, or SQL Server Management Studio connection.

Resolution:   (applies to MSSQL 2005, 2008, and 2008 R2)

1. The Windows firewall is usually the culprit in these scenarios. Open TCP port 1433 for the service itself, and 1434 if the customer needs to use the SQL Browser service.  Read this article to learn how to Open an Inbound Custom Allow Rule in Windows Firewall.
2. Open “cliconfg” (yes, it’s spelled like that) from a Run prompt and make sure TCP/IP is an enabled protocol.
3. Check the Services tool (Start, Administrative Tools, Services) to see that the service named “SQL Server (MSSQLSERVER)” is started.
4. Ensure that you are using the correct credentials to authenticate. The default SQL administrator account is named “sa” and if you built the server from one of our server images with MSSQL pre-installed, the password will be in a text file on the root of the C partition.
5. Use “netstat –an” from the command prompt to see if the server is listening for SQL traffic on the correct ports.
6. If not, use SQL Server Configuration Manager to change the ports. 

• Start, All Programs, Microsoft SQL Server 2008 (or 2008 R2), Configuration Tools, SQL Server Configuration Manager
• Open the + next to SQL Server Network Configuration
• Right-click TCP/IP and select Properties
• Select the IP Addresses tab
• All TCP ports mentioned on all interfaces should be 1433, change to reflect the correct port number and restart the SQL services.