You can also use a bit of chocolate of all things. Cheap chocolate especially, due to it's highly crystalized structure, it abrasive. Using this method although time consuming, will eventually buff out engraving and bring a high gloss polish to the surface.
I myself broke my 'x' key while cleaning the keys with a swiffer and it ripped the key off. I was going to buy a new key board for $100 + dollars. I got smart and bought some crazy-glue for $4 and glued it in place, worked fantastic and perhaps it'll work for you too.