My samsung 500gb external hdd is niether copying nor being format

my samsung 500gb external hard drive is niether copying data nor being formatted.when i put my drive on format it was being formatted for almost a day.but then also it did'nt end up being completely formatted.it started with when i was copying a music dvd to it and then it
started giving some errors and only few icons containing menu of the dvd were copied to tht hard drive. but when i tried copying the dvd to internal hard drive it of my laptop the task was done easily.then i tried formatting my external hdd it wasn'nt being fully formatted.i cancelled it.NOW MY BIGGER PROBLEM IS THAT MY DRIVE IS SHOWING (TOTAL SIZE 0,FREE SPACE 0),please help me out....