When I am storing Chinese language in my database from my C# application its showing “????” but when I am manually adding the value to database its storing proper Chinese string.

Note : I have a column of nvarchar type, manually when I am adding the value to that column i am using N prefix before that. But through code I don’t know why its not taking.
I tried to use N prefix in the code also but its taking it as a string and saving in DB as “N’????'”.
DB – SSMS
Stand alone Application – C#

I expect that it should take the input from user and store that in Name column, either the value is in Chinese or English.