Cd/Dvd-Rom is not being detected or opening

Hello,

I am having a huge problem. I take online courses and it is required we load certain programs and such on our computer. Well one day I went to load the disk I needed, and my Cd-rom wouldn't open at all, except when you hit the little reset button which automatically opens it. I have noticed that the drive opens first thing when the computer turns on but when the loading page comes up, which is like 10 secs later, it doesn't open at all. The CD-ROM light is ALWAYS blinking as if there is a disk in it loading but there is not. I am having a hard time figuring this out. But it is only detected whenever the computer first starts, you can open and close constantly for like 15-30 seconds, but after wards when the computer starts loading, it's NOTHING. In the device manager, there is no option for CD/DVD-ROM available. PLEASE HELP...