No volume control, icon or laptop buttons

Hello,
I have a compaq presario v2000. After getting a virus I can no longer control the volume through the volume icon (as I don't have the icon and can't get it even when clicking on the relevant place in the control panel) or through the buttons on my laptop. I do get sound but can't turn it up, down or mute it through the laptop buttons, howeve when going onto the sounds in the control panel I can turn the volume up and down. I don't have any error messages appear. I have read some other forum posts advising to download a driver but I already have a driver. I have also read to copy the sndvol.exe from a working computer to the Windows folder on my computer but this didn't work either. I no longer have the start up Windows XP cd but do have some information save on the computer from a previous back up.

Does anyone have any suggestions on how I can get the laptop buttons to work and or to get the volume control back n the tasbar as it is starting to et very annoying?