window server da database a bağlantı

Programlamaya hakim biri değilim, ama yapmam gereken bir iş vardı. Windows server 2008 e .net de yaptığım proje için database e bağlanamıyorum. Local de yaptığım çalışıyordu ama server a bağlandığımda artık çalışmıyor projem. sürekli şu hatayı alıyorum:

A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified) 

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 

Exception Details: System.Data.SqlClient.SqlException: A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified)

Nasıl bağlanabilirim? ne yapmam gerek acaba..