No audio after various options tried

Hello,


my problem began by turning off computer during shutdown as it was taking ages to update. when i turned on cpu again it kept rebooting. I then re-installed windows xp. since then everything works perfectly except audio.
ive followed numerous advice on net such as installing realtek driver/ checking that windows audio is on etc, when i click on properties on all sound related option its says ''working perfectly etc. the sound icon on bottom right isnt there and the option to select is greyed out saying '' no audio device'' , ive reinstalled audio and checked for hardware updates. im using a HP pavillion A1000 with windows xp home edition. would really appreciate some help. id rather have audio on my computer than any other option ie internet/games etc.