Hi prajapatiamit2003,

What is the SQL server 2005 edition in your connection string? Is it a SQL server 2005 Express edition?

We can attach or visit the database file in “App_Data” folder with “AttachDbFilename=|DataDirectory|\Test.mdf;” in SQL Server 2000 Express edition, so if it’s other editions of SQL Server, you may attach the database file in the “SQL Server Management Studio” , then remove the “AttachDbFilename=|DataDirectory|\Test.mdf;” from the connection string and modify it as usual.  

<add name="SqlServer" connectionString="Server=yoursqlservername_or_IP;
userid=yourdbusername;password=yourdbuserpassword;database=databasename"
providerName="System.Data.SqlClient"/>