How to keep values in Text box and Drop Down box when validation fails

[Priya]

 I have a radgrid that uses Add New Record to enter data, then uses the server side validation to make sure that the User Id field is not duplicated in the database.  When the server side validation fails, I display a message why the insert failed. To keep the insert mode, I use e.Canceled but values are lost.
 I can't figure out how to keep the values in the textboxes after the server validation fails so the user won't have to retype everything. 

Thanks in advance.