How to filter special characters from user input?

Problem:
I am using a textbox to capture user entry to create a custom SQL select statement. I have everything working fine but I get an exception thrown when I wanted to search by city name and I entered, "Cox's Bazar" in the textbox.
Solution:
In this case you need to filter special characters from user input values that produce this error. You can filter user inputs using following method in your string helper class:


        /// <summary>
        /// Replace UnWanted Character from string
        /// </summary>
        /// <param name="input">Input string</param>
        /// <returns></returns>
        [DebuggerStepThrough()]
        public static string ReplaceUnWantedCharacter(string input)
        {
            input = input.Replace('+', ',');
            input = input.Replace("--", "++");
            input = input.Replace('&', ',');
            input = input.Replace("%", "[%]");
            input = input.Replace("_", "[_]");
            input = input.Replace("[", "[[]");
            input = input.Replace("]", "[]]");
            input = input.Replace("'", "''");
                        return input;
               }

the use of this method may be like:
string cityName = StringHelper.ReplaceUnWantedCharacter(txtCityName.Text.Trim());