CD/DVD Drive Missing from Device Manager

Hello,
I have an HP with Vista. My pc came with a built in cd/dvd player which has worked fine up until recently. It's not reading anything or acting like it's running. After reading other post online I checked my Device Manager and cd/dvd is not listed. How can I install it if it no longer exist? Someone please help! I can't download necessary hardware without it.

Thanks in Advance!