using System;

using System.Globalization;

using System.Text;

​

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Héllo-Wïrld");

        Console.WriteLine("Héllo-Wïrld".NormalizeDiacritics());

    }

}

​

public static class StringExtensions

{

        public static string NormalizeDiacritics(this string text)

        {

            if (text == null) return null;

            var stringBuilder = new StringBuilder();

            foreach (var c in text)

            {

                var unicodeCategory = CharUnicodeInfo.GetUnicodeCategory(c);

                if (unicodeCategory == UnicodeCategory.NonSpacingMark) continue;

                var a = c.ToString().Normalize(NormalizationForm.FormKD).ToCharArray();

                if  ((a[0] >= '0' && a[0] <= '9') || (a[0] >= 'A' && a[0] <= 'Z') || (a[0] >= 'a' && a[0] <= 'z') || a[0] == '-' || a[0] == '_')

                {

                    stringBuilder.Append(a[0]);

                }

            }

            return stringBuilder.ToString().Replace("&", " ").Replace("'", " ");

        }

​

}