各位大神们帮忙解决一下吧 急啊 实在是看不懂啊！

[SqlException (0x80131904): 在与 SQL Server 建立连接时出现与网络相关的或特定于实例的错误。未找到或无法访问服务器。请验证实例名称是否正确并且 SQL Server 已配置为允许远程连接。 (provider: SQL 网络接口, error: 26 - 定位指定的服务器/实例时出错)]
   System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection) +6256377
   System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj) +245
   System.Data.SqlClient.TdsParser.Connect(ServerInfo serverInfo, SqlInternalConnectionTds connHandler, Boolean ignoreSniOpenTimeout, Int64 timerExpire, Boolean encrypt, Boolean trustServerCert, Boolean integratedSecurity, SqlConnection owningObject) +6270399
   System.Data.SqlClient.SqlInternalConnectionTds.AttemptOneLogin(ServerInfo serverInfo, String newPassword, Boolean ignoreSniOpenTimeout, Int64 timerExpire, SqlConnection owningObject) +181
   System.Data.SqlClient.SqlInternalConnectionTds.LoginNoFailover(String host, String newPassword, Boolean redirectedUserInstance, SqlConnection owningObject, SqlConnectionString connectionOptions, Int64 timerStart) +6271401
   System.Data.SqlClient.SqlInternalConnectionTds.OpenLoginEnlist(SqlConnection owningObject, SqlConnectionString connectionOptions, String newPassword, Boolean redirectedUserInstance) +6271208
   System.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString connectionOptions, Object providerInfo, String newPassword, SqlConnection owningObject, Boolean redirectedUserInstance) +354
   System.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions options, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningConnection) +703
   System.Data.ProviderBase.DbConnectionFactory.CreatePooledConnection(DbConnection owningConnection, DbConnectionPool pool, DbConnectionOptions options) +54
   System.Data.ProviderBase.DbConnectionPool.CreateObject(DbConnection owningObject) +6272472
   System.Data.ProviderBase.DbConnectionPool.UserCreateRequest(DbConnection owningObject) +81
   System.Data.ProviderBase.DbConnectionPool.GetConnection(DbConnection owningObject) +1657
   System.Data.ProviderBase.DbConnectionFactory.GetConnection(DbConnection owningConnection) +88
   System.Data.ProviderBase.DbConnectionClosed.OpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory) +6275911
   System.Data.SqlClient.SqlConnection.Open() +258
   Microsoft.Practices.EnterpriseLibrary.Data.Database.GetNewOpenConnection() +242
   Microsoft.Practices.EnterpriseLibrary.Data.Database.GetOpenConnection(Boolean disposeInnerConnection) +74
   Microsoft.Practices.EnterpriseLibrary.Data.Database.ExecuteReader(DbCommand command) +48
   PowerEasy.Framework.Database.DBHelper.ExecuteReader(CommandType commandType, String strCommand, Parameters cmdParams) +185
   PowerEasy.Module.General.DataAccess.Contents.NodesDal.GetNodeBySubDomain(String subDomain) +636
   PowerEasy.Foundation.HttpModule.DomainModule.Application_BeginRequest(Object source, EventArgs e) +365
   PowerEasy.Foundation.HttpModule.BaseHttpModule.Application_BeginRequest_Handle(Object source, EventArgs e) +49
   System.Web.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +80
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +171
--------------------编程问答-------------------- 自己顶一下 --------------------编程问答-------------------- 别顶了，这个错误自己google方法一大堆，自己对照着情况试试吧，不是网络问题就是服务器无法访问，要么就是sql的一些设置没打开 --------------------编程问答-------------------- http://blog.csdn.net/yycc2008/article/details/3985005
然道百度会比在这里问速度要快吗 --------------------编程问答-------------------- 就是 没连上Sql Server 大概就几种情况吧。百度

补充：.NET技术 ,  ASP.NET