using System;

public class Program

{

    public static void Main()

    {

        var val = (object)"3BB71BB5-02EF-4DF7-94B3-FFF99FFE4AE8";

        var t = ParseValue<Guid>(val);

        if (t == null)

            Console.WriteLine("NULL");

​

        Console.WriteLine(">>" + t + "<<");

    }

    static T ParseValue<T>(object value)

    {

        if (value == null || string.IsNullOrWhiteSpace(value as string))

        {

            return default(T);

        }

        if (value is string)

        {       

            return (T)Convert.ChangeType(value as string, typeof(T));

        }

​

        var converter = System.ComponentModel.TypeDescriptor.GetConverter(typeof(T));

​

        return (T)converter.ConvertFromInvariantString((string)value);

    }

}