You will stuck literally everytime when you try to insert date in databse from C#. I always got stuck in this situation. Then finally I find one solution that works. Best way to do is create a text box in asp.net like this:
In backend C#, get textbox data as string:
In sql server store procedure, insert date through this method:
if will insert date into dd/mm/yyyy format.
This is the easiest way to insert date into database.
Hope this helps. :)