My Laptop Does Not Sounds At All, Please Help

hi i have a Compaq Evo N600c laptop with windows xp sp2 installed, which is not giving any sound at all not even windows startup or log out sound, i tried everything, i uninstalled and reinstalled my sound driver, i updated my sound driver, i checked the bios its upto date, once i even reinstalled the windows but still no sound. my control panel and device manager shows that the sound device is working fine.

i am having this problem from long ago but it was working fine since yesterday when it suddenly stop giving sound in the middle of a song playback.

whenever i plays an audio file the time bar does not move at all its on 0, my system gets stucked for a while, and no sound at all, whereas when i play a video file my system gets stucked in the start for a while then the video plays for like 5 seconds without sound and stops, i have to click on the time bar every 5 seconds in order for the video to keep playing.

Any help please