No input/output Audio Devices

MacBook 13" Unibody (Model A1342) Mid 2010 , Mac OS X (10.6.8)

The sound suddenly stopped. On System Preferences, on Audio, it shows the sound as muted and doesn't allow me to unmute it. System Profiler shows Audio (Built-in): Intel High Definition Audio: Audio ID - 0, no input/output Audio Devices. I fixed the hard drive access permission , did the reset for both pram and smc several times and finally installed a clear copy of mac OS after deleting the HD, but unfortunately ended with no success. Do you think it is a hardware related problem? How do I fix this?

 Thank you in advance.