"It does not exist any more."
Translation:Den findes ikke mere.
What is the difference between "den" and "det" when starting this sentence? I presume "den" is for "-en" and "det" "-et" words, so which one should be used when it has not bee defined yet?
You're correct with your presumption. And you should know what you're talking about when you say that it doesn't exist. :D
But if you really have no clue whatsoever, use det.
Any more (two words) is reserved for the meaning even the smallest amount. In other words, when used as a determiner, the two-word spelling any more is used. Anymore (one word) is reserved for the meaning any longer. In other words, when used as an adverb, the one-word spelling anymore is used. Anymore should be used here, I believe .