Ok, so my natural hair color is brown, and yesterday I had it professionally dyed it black. I absolutely hate it, and I was wondering if there's any product (shampoo) that could get the black out, and my natural hair color back quickly.

Just a word of caution, trying to fix it yourself could make it worse. If you're not careful you could over process your hair and just totally fry it or something. I would suggest going back to the salon and explaining that you hate it and want them to fix it.