CD Rom Problems

I have a laptop that is running windows 98, is a pentium III, 450Mz. A few years ago, my cd-rom died and computor tech said cheaper to buy an external one which I did, A Polariod Burnmax 24EX. Things were going find. Then My disc detector tells me “no drives detected”. I know the external works, because connected it to my desktop. I know USB port works, connected another device. I found that the laptop is reading my d (internal CD Rom) and F which is supposed to be my external, as one and the same D the internal drive. I know this because clicking on both drives opens the internal drive. HELP, What do I do. I’m a grandmother raised on slide rules, but have a little computor knowledge.

Thanks for your help