after going Offline and resolving it, my HP Envy 4500 will not stop printing and says printing

I have an Envy 4500 Serial CN4AL 155VX,Something happened and it would not print and the computer said Offline. I kept sending things to print over and over until I found the offline message. I think I found the problem so the first thing came through. Now the printer will not stop printing. Some sheets are blank others keep prints something I sent through later. I unplugged the printer but when I turned it on it would say printing and I would push the cancel button . What should I do.