if it is in its slot the next thing to check is whether it is functioning. does it open when you push the little button, if it does it is working, if not it has probably failed but this is not a definitive check. does the little green light flash when you turn on the machine, if so good. if it will not install when the Machine is turned on more than likely it has failed. try taking it out of the slot. you will need to take two screws out of the bottom of the machine. reinsert it, making sure it seats fully and snugly into the socket. if it doesn't have a flashing LED and doesn't open and close then it has failed. a failed drive will not automatically or manually install.