Inaccessible boot device won t boot up?

win2000 profesional cant boot computer inaccessible boot device.can some one please tell me were to go to down load a free boot up disc and which part do i down load and do i save to comp then burn to disc i need it in simple terms because im not a computer wizz.i dont have a a boot up disc tried the start in safe mode ect but cant get that far it comes up stop inacessible boot device so done all the basics ...thanks