I was browsing for a file to attache to an email and I accidentally dragged the Desktop icon from the side menu, and it dissappeared

Hi all, I have read through the posts here but none of the solutions have worked so far. What happened in my case is I was browsing for a file to attache to an email and I accidentally dragged the Desktop icon from the side menu, and it dissappeared in a puff of smoke!

I didn't even know this was possible but now finder does not display a desktop icon which is endlessly frustrating.

I'm using Snow Leopard Version 10.6.8. Any ideas? Thanks :-)