Try taking the drive out and putting it back in seems like the drive is not getting power.
Can't really assume that just yet. The 'cd rum' could be broken, it could be a problem with power, it could also be a problem with the cable, and if its IDE it could be set to slave/master when there already is a slave/master...
Need some more information on what is happening. Try going into your BIOS and see if it is reading it in there. If it isnt shown then most likely something is wrong with your connection to the mobo or power supply.