If i have a Nikon D3100, knowing it does not have a Mic input, can i use this?

Http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=130600012946#ht_3252wt_1344

If you have anymore suggestions please tell me.

Added (1). I clearly know it does not, but why would the sell it, knowing it doesn't have an input. The title of the item clearly says for Nikon D3100?!

I'm afraid you can't! If you look at the tip of the mic your planning to buy, you can see that it obviously plugs into something, and that something could only be a mic input. I guess the eBay seller must not have looked into the product the mic is for.
Sadly, there's no way you can use a mic with the Nikon D3100:(
If I were you, and if you are starting to get serious about film-making, I would buy a used Canon 550D (I only say used if you are quite short of money).

You've already answered your own question… No mike input, no external mike - answer - nope.