DateTime dtStart = TimeZone.CurrentTimeZone.ToLocalTime(new DateTime(1970,1,1));
DateTime dtNow = DateTime.Parse(DateTime.Now.ToString());
TimeSpan toNow = dtNow.SuBTract(dtStart);
string timeStamp = toNow.Ticks.ToString();
timeStamp = timeStamp.Substring(0,timeStamp.Length - 7);

string timeStamp = "1288368000";
DateTime dtStart = TimeZone.CurrentTimeZone.ToLocalTime(new DateTime(1970,1,1));
long lTime = long.Parse(timeStamp + "0000000");
TimeSpan toNow = new TimeSpan(lTime);
DateTime dtResult = dtStart.Add(toNow);