Converting characters and accents to "regular characters"

gistfile1.txt

void Main()
{

	Console.WriteLine(RemoveDiacritics2("PIŁKI"));
	  
}
    public static string RemoveDiacritics2(string text)
    {
      if (!string.IsNullOrEmpty(text))
      {
        string str = Encoding.UTF8.GetString(Encoding.GetEncoding("ISO-8859-8").GetBytes(text));
        if (str.Contains("?"))
          str = NormalizeStr(text);
        text = str;
      }
      return text;
    }
	
	public static string NormalizeStr(string text){
	    StringBuilder stringBuilder = new StringBuilder();
      string str = text.Normalize(NormalizationForm.FormD);
      int num = str.Length - 1;
      int index = 0;
      while (index <= num)
      {
        char ch = str[index];
        if (System.Globalization.CharUnicodeInfo.GetUnicodeCategory(ch) != System.Globalization.UnicodeCategory.NonSpacingMark)
          stringBuilder.Append(ch);
        checked { ++index; }
      }
      return stringBuilder.ToString();
	}
	
	  public static string RemoveDiacritics(string text)
    {
      if (!string.IsNullOrEmpty(text))
      {
        string str = Encoding.ASCII.GetString(Encoding.GetEncoding("ISO-8859-8").GetBytes(text));
        if (str.Contains("?"))
          str = NormalizeStr(text);
        text = str;
      }
      return text;
    }