G.K.
I'm assuming you mean a stainless steel cooktop? Mine was stained for two years until a month ago when I found a solution. I had tried several different stainless steel cleaners and none worked on the stains. Then I finally remembered my mom using these funky stainless steel scrub pads (I can't remember exactly what they're called, but they look like long strings of silver tinsel woven together into a ball, and the packaging will say that they are specifically for stainless steel. I got them at Target next to the regular sponges. They're not "steel wool" which I think will scratch...) I tried it with just water and it got EVERYTHING off--stains that had been there for two years--in about two minutes!!!
At least I'm not the only one who managed to stain a "stainless" cooktop! Hee hee!