My laptop charger isn't working.?

I have had a Dell Inspiron 14R (N4010) laptop computer for about eight months. Two weeks ago, almost every time I would go to charge it, a message would pop up on my computer and say "The AC adapter type can not be determined. Please use a Dell 65W AC adapter." Then, last week, the charger just quit working completely. My charger gets the power because the charge light comes on for about two seconds and then goes off and then continues to display the error message. Please help. I'm confused.