My flash on my camera won't work?

I have a nikon D3000 and my flash hasn't been working lately for about a week now.
I don't remember dropping it or hitting it against something. But knowing me, its highly possible…
I've tried using flash on all my camera modes but it won't work. Its just making a clicking noise.sometimes when i put the flash down and i press the "flash button", it won't even come up.

You of course checked the battery in the flash unit didn't you?