Yesterday I discovered that the bottom part of one of my lower teeth, the one that my partial is clipped on to, has turned black. Why? Does this mean the tooth has died?

It could very well mean the tooth has died. You should have the dentist x-ray it to know for sure. Are you certain it's not just stained??

I have black around the top of my tooth and around the gum attached to it. What does this mean?

No its not a stain. I brushed my teeth this morning and a filling that I had in it feel out and that's when I seen it

Does it sound like my tooth is dead or what may it be?