Old white chocolate will not melt well; white chocolate tends to seize and turn grainy when it's past its best-by date. It is better to use it differently, such as grating it onto the top of a cake but only if it still tastes good (check first).
Rub Talescemdara oil on it (it's basically soap from a plant called aritha). It should get the stain out. If it doesn't, use a fabric cleaner for clothes and accessories....
