try This :
IFormatProvider theCultureInfo = new System.Globalization.CultureInfo("en-GB", true);
DateTime from_date = DateTime.ParseExact(string1, "dd/MM/yyyy", theCultureInfo);
DateTime to = DateTime.ParseExact(string2, "dd/MM/yyyy", theCultureInfo);
this will convert your string into Datetime Object.
Hope this will help you.