Hi Karen!I lost the sound on my Packard Bell about 3 months ago. One day when I had a bit of time, I got down on my hands and knees with the thing and I realized that, when I had unplugged a cable while dusting, I had replugged it in the wrong jack. I know, Karen, that you have feel you have it properly connected but it might be worth yet another examination if you have multiple jacks that accept similar plugs.
If not, I hope the 10 quid sound card will get you fixed up.
All the best,
Dan