Andy is right. Strokes with a tissue from the centre outwards, but if it's a nasty scratch or stain, there is a device marketed under various names, (DVD Doctor, CD Doctor etc) which actually takes a layer off the disc and should remove, without damaging the disc, (further) your problem. It costs about �30, but could save your CD, (or whatever) collection!!!! I've had no problems with it and it's paid for itself threefold at least. You might also want to know that water does not damage discs at all, as long as you dry them thouroughly before you use them again.