if those drivers are not there, then it means you installed a pirated XP.
just run the "Standard System Recovery", XP will Install with all drivers...,
IF you COMPLETELY Formatted the HDD
or DELETED the Recovery Partition, then only option for you is to run "FULL System Recovery" .
WARNING:
if you run Full System recovery, you'll LOSE ALL DATA & Partitions IN HDD.
So better have Back-ups of the neccesary files

before doing that.
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to have the sound back- the other way around is to have XP SP2 patch.
I strongly reccomend you to install XP from the Recovery Disks provided by HP.
coz you HAVE a GENUINE version of XP, so why use a pirated thing