在Visual Studio 2017的asp.net中的数据库中插入值时出错

错误信息：

System.Data.SqlClient.SqlException
建立与SQL Server的连接时发生与网络相关或特定于实例的错误。服务器未找到或无法访问。验证实例名称正确，并且已将SQL Server配置为允许远程连接。

web.config：

<system.web>
    <pages enableEventValidation="true"/>
    <compilation debug="true" targetFramework="4.6.1"/>
    <httpRuntime targetFramework="4.6.1"/>
</system.web>

register.aspx.cs文件：-

protected void r_submit_Click(object sender, EventArgs e)
{
    SqlConnection conn = new SqlConnection(@"Data Source = (LocalDB)\\MSSQLLocalDB; AttachDbFilename = C: \\Users\\Abhishek\\Documents\\Visual Studio 2017\\Projects\\S2N\\s2n\\App_Data\\Database.mdf; Integrated Security = True");
    {
        conn.Open();

        SqlCommand cmd = new SqlCommand("insert into register values(@fname, @lname, @dob, @email, @mobile, @passoword)",conn);

        cmd.Parameters.AddWithValue("fname",fname.Text);
        cmd.Parameters.AddWithValue("lname", fname.Text);
        cmd.Parameters.AddWithValue("dob", dob.Text);
        cmd.Parameters.AddWithValue("email", email.Text);
        cmd.Parameters.AddWithValue("mobile", mobile.Text);
        cmd.Parameters.AddWithValue("password", password.Text);

        cmd.ExecuteNonQuery();

        fname.Text = "";
        lname.Text = "";
        dob.Text = "";
        email.Text = "";
        mobile.Text = "";
        password.Text = "";
        fname.Focus();
    }
}

请帮我