Deleted Launchpad

Hi,

Launchpad has a question mark over it and doesn't work.

For some mysterious reason, a while back a second Launchpad icon attached itself to the bottom left of my toolbar. I never used it. A few moments ago, I decided to get rid of it. So I trashed and deleted it.

I still have the original Launchpad icon, which is the only one I've ever used to open programs, but now it doesn't work. It doesn't open, and like I said, there's a question mark over it.

I tried to drag and drop the Lanchpad icon from Applications onto it, but it just bounces back.

Any ideas?

Thanks,

Matt