If you can't change the date your storing to a UTC time and convert back and forth when inserting and selecting data. Then unless your data is being inserted at the server you're going to have to record something that tells you where the data came from (i mean what the local time zone is of the client that inserted the data).
If your data is only getting inserted at the server then you can probably use the SQL Functions GetUTCDate and compare it to GetDate, then subtract the result from your datetime stored in the database. Then at the client use DateTime.ToLocalTime() to convert the returned value to local time. As I said this will only work if the data is exclusively inserted at the server or at least by clients in the same time zone. Otherwise forget it.