You do not have to throw away the metal silverware. They can be made kosher again (a process referred to as kashering) in the following manner:
Don't use the silverware for at least twenty-four hours. Then clean them thoroughly. Afterwards, boil water in a pot (it doesn't matter if it is a meaty or milky pot). Once the water is boiling and bubbling, keep the flame on high so the water doesn't stop bubbling and immerse the silverware into the boiling, bubbling water. After they have been completely immersed in the boiling water for a moment they must be removed and placed in a pan of cold water. A word of caution - do not take the silverware out of the boiling water with your hand!
Unfortunately china cannot be koshered. Therefor you have to dispose of the plate.
