C# windows form sql database deleting problem

Well, it's how identity seed works in table.

If you delete a record with ID as 1 and there are 8 records in table, next insertion starts with ID as 9 and not 1.

If you still want to make it possible, you need to turn on identity insert option for that table. And then do insert operation with primary key (meaning insert with ID=1, make sure that you removed record with ID=1, else it may result in error).

It is not the ideal solution but possible. Other option is to have separate column with question ID without identity constraint(which requires table design change-kind of hmm) and maintain the list of deleted questions (in C# code) and then insert using deleted question IDs.