WATER!!! Sooo, the piston is'nt hurt? Could you have sucked some water in while riding. If so, Water in a cylinder is very, very bad. It will hydraulic and bad things will happen.
If you have studs missing, you need to take that to a machione shop and see if he can fix it. Do the right or if done wrong, you can be in the same place a week from now, go ahead and have him bore and hone it (buy piston and rings first)...