public static string OdstranDiakritiku(string Text)

        {

            string stringFormD = Text.Normalize(System.Text.NormalizationForm.FormD);

            System.Text.StringBuilder retVal = new System.Text.StringBuilder();

            for (int index = 0; index < stringFormD.Length; index++)

            {

                if (System.Globalization.CharUnicodeInfo.GetUnicodeCategory(stringFormD[index]) != System.Globalization.UnicodeCategory.NonSpacingMark)

                    retVal.Append(stringFormD[index]);

            }

            return retVal.ToString().Normalize(System.Text.NormalizationForm.FormC);

        }

        public string OdstranSpecialniZnaky(string str)

        {

            return Regex.Replace(str, "[^0-9A-Za-z ,]", "");

        }

​

string bezZnakuOT = string.Empty;

char[] OT = OdstranDiakritiku(tB_otevrenyText.Text.ToUpper()).ToCharArray();

bezZnakuOT = OdstranSpecialniZnaky(OT.ToString());