Have you setup your drives master/slave settings properly? Are the lights on on the drive and is the cd/dvd spinning up when you insert it? If not, your power cable may not be in. Have you made sure your IDE cable is seated properly? All first things I would check. Does explorer even recognize the drive(can you see it in My Computer)? More info please
edit:
Wait, I just reread this...you mean BOTH drives aren't working? Are then on the same IDE? It sounds like you either have the master/slave setup incorrectly, or your ide isn't seated properly on your motherboard. Open it up and take a look