System formatted unknowingly

Hello,
my name is vijay formatted system unknowingly and somehow he managed it,and completed and he also removed the door of the cpu and he reinserted the RAM into the computer and system is not formatted thoroughly. i want to format that system once as when i inserted the OS cd the message has been displayed has file error has been occured press any key to cancel and there is no booting of the cd. i also found missing of the icon of DVD drive in mycomputer its not shown in any of the components present in the dvd. so plz solve the problem.