c# build or pressing f5 seems like autopress the Delete key where ever my cursor pointed at

Question

this is my code before i press the build or F5 button

        using (var context = new DeliveryDriverContext())
        {
            return (from a in context.STNKs //my cursor is here
                    where a.PlatNo == platNo
                    select a).FirstOrDefault();

        }

and when i Build the project or press the f5 button the code become like this

        using (var context = new DeliveryDriverContext())
        {
            return (from a in context.STNKswhere a.PlatNo == platNo
                    select a).FirstOrDefault();

        }

and of course it cause errors at that line,and its annoying. is there anyone know how make like it used to be,pressing f5 or build without changing anything