I colored my hair 3 days ago from light brown to almost black and when I was washing the liquid dye out I thought I got it all, but 3 days later there is still liquid dye that I can't seem to get out of my hair. What do I do?

It is natural for hair color, especially dark ones, to continue to wash out and fade a bit for a few weeks after the initial application. Washing with a color-saving shampoo and conditioner from a salon, such as Biolage or Bumble2Bumble (cheap store brands like Aussie and Pantene will not deliver good results, but will merely mask hair's imperfections with a layer of wax, while salon or higher-end brands will actually nourish hair and protect color) can help dye from fading, which is probably part of what you're seeing. Rinsing hair with hot water will also help remove more of the excess dye, whereas cold will help hold it in.