Here is a guide that will help you solve your problem. Since you didn't provide the model of your computer, I don't know if they will still be available from HP. If not, try this source: http://www.computersurgeons.com/
Please click the Thumbs up + button if I have helped you and click Accept as Solution if your problem is solved.
I am not an HP Employee!! Intelligence is God given. Wisdom is the sum of our mistakes!!