No audio output device

My HP Pavilion DV9000 laptop has no sound. During Device Manager does not show any sound. I had sound, it worked, but today I had nothing. I have a Windows 7 Ultimate on it. I do not understand anything. What could be the cause?
thank you

Those HP dv9000's run hot and it is possible that the sound chip on the motherboard has failed... If this is the case, there should be a yellow exclamation point on the audio device driver in the device manager

Hello,
I have no exclamation mark,nowhere
Thanks

List any Problem devices

• Make sure devices are connected and powered on
• Click Start->Run, enter: msinfo32. Click the + sign next to Components to expand it
• Click Problem Devices. Anything appear?
• If yes, click on it, Ctrl-A to select all, Ctrl-C to copy it, Ctrl-V to paste into next post
• On the other hand, if no devices are listed, tell me so

Generate and attach a DirectX report

• Click Start->Run, enter dxdiag and click OK
  ===> If you’re running 32 bit Windows, dxdiag will launch on its own
  ===> If you’re running 64 bit Windows, you’ll see 64-bit DxDiag. Click it to launch the 64-bit version of dxdiag
• Notice progress in lower left window corner
• When done, click Save Information button and save as a text file to your Desktop
• Attach it to your next post by clicking the Upload a File button