PCI SLOTS not working? TV Tuner and Sound Card

I have a TV Tuner, that worked fine, also with a sound card that was going great, but when my TV tuner stopped working I switched PCI slots and now my sound card doesnt work either. When I run the setup, and try to load the drivers, it says, can not find the hardwarel. Basically how do I get my computer to see that I have something in my PCI Slots. I tried add new hardware, I tried Bios (well seaching around for something) I tried unplugging, then rebooting, then plugging it all back in and then rebooting. Also tried reinstalling the software and drivers. Where do you think the problem is?