There is also a "switch" in the jack that you plug those speakers into that fails. BEWARE: That is not something your end users change out. It requires finding the replacement part, disassembly of the machine and fine solder skills to change.
At 4 years I'd not fix this but use headphones.
Or the speakers came unplugged inside the laptop?
I have a four year old HP Pavillion windows xp and there is no sound. I checked the settings and control panel. I can only receive sound if I hood up speakers. I assume the speakers are "dead". Is this common?