kind of depends how bad it is. The engine I just put back together today, the corners of the valve were bend down so I couldnt pull it out. I used a dremel and cut down the bends as good as I could and used a punch to dive it out. Keep in mind i had the cylinder on the bench while doning it. My guess in your case is a similar problem and you will need a new one, but try puting a visegrip on the end and see if you can maybe tap it out.
