My Hp laptop display not work

sir i have a Hp laptop averithing is ok but display is not[ just dark] screen i will testad flowing parts
ac adpater,battry,ram,but windows run proparly give soumd display can not apper -plese give your`s best seageson

Your nvidia chipset must be damaged. This occurs in certain older hp laptops due a faulty fan algorithm. It has been resolved in the new bios update. Certain models with this issue are eligible for warranty extension and free repair. To check if your model is among them checkout the following post :
http://pitstop87.blogspot.com/2009 [...] ecall.html
It will give you all the details and links that you need. I hope this reply is useful to you. It's the only solution i can think of to your problem cause the problem sounds very similar to the one described in that post.