How do I fix the sound on my computer?

I just purchased a new sound card (Sound Blaster X-fi Titanium), installed the hardware and then the software. It was working for about 2 days, then, after I installed a new hard drive(not exactly sure if it was directly afterward), it stopped working(also, I must mention my computer kept shutting off several times because of a thunder storm. Hoping my cards not fried :x but that shouldn't affect my on board audio, right?). I uninstalled the drivers and then reinstalled them several times(for the card and the on board audio), but nothing has changed. I also disabled on board audio in the BIOS to see if that would help, but it hasn't. Now, whether on board audio is enabled or not, I get no sound from the on board audio or the card. Also, when I go into the device manager, there are no sound devices listed. What do I do? Help is much appreciated.