No Audio Output Device Installed

Hello, I have a hp pavillion dv6810us running Vista that has lost sound, error message "No Audio Output Device Installed. The error message is ...
Problem signature:
Problem Event Name: APPCRASH
Application Name: HPKBDAPP.exe
Application Version: 1.0.0.4
Application Timestamp: 46dcf199
Fault Module Name: HPKBDAPP.exe
Fault Module Version: 1.0.0.4
Fault Module Timestamp: 46dcf199
Exception Code: c0000005
Exception Offset: 00002a3f
OS Version: 6.0.6002.2.2.0.768.3
Locale ID: 1033
Additional Information 1: 70f7
Additional Information 2: 676905ecbfac1800dcd2fd9d2e19ba88
Additional Information 3: 1358
Additional Information 4: 08325acb2ebc883152deed3984d3dc18
Just yesterday the computer overheated and shutdown, when it came back on the sound worked until the computer shut down from non use. When restarted I am getting no sound again. How to fix?