using System;

using System.Globalization;

​

public class Program

{

    public static void Main()

    {

            string data = "2023-03-01 08:30:02.000";

            var format = "yyyy-MM-dd HH:mm:ss:fff";

            var convertedBack = DateTime.ParseExact(data, format, CultureInfo.InvariantCulture);

            Console.WriteLine(convertedBack);

    }

}