HP Pavillion 734n comes with XP installed on a hard drive partition. Through viruses and other mishaps it has become damaged. I installed XP from a cd, but I have no sound except for the internal speaker. It always worked before.

Sounds like you need to reinstall the sound card drivers. Is the sound card built in to the motherboard or is it a PCI card?

This should be the driver for the default onboard sound.

http://h10025.www1.hp.com/ewfrf/wc/s...&dlc=en&os=228