How to Convert a Value to a Type when both defined in String?

static void Main(string[] args) {
    Object result =
        ConvertValue(
            "System.Nullable`1[[System.DateTime, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]]",
            "2012-02-23 10:00:00");
 }

 public static Object ConvertValue(string typeInString, string value) {
    Type originalType = Type.GetType(typeInString);

    var underlyingType = Nullable.GetUnderlyingType(originalType);

    // if underlyingType has null value, it means the original type wasn't nullable
    object instance = Convert.ChangeType(value, underlyingType ?? originalType);

    return instance; }