Have an innormous problem with the cd rom

Hello,
I m azhar. I have an acer machines e727. It was working fine few days back. But suddenly my cd rom stopped working. It is not shown in device manager. I have tried microsofts fix. But as it is not in device manager i cannot fix that. I also tried upper n lower filters. But those are not there. I m using win 7 ultimate. I tried updating driver but i cant do that because i dont know how to do it. And also forgot to say a thing. That is even if i press the button on the cd tray it does not open and the light of the cd tray is always glowing. Its not flashing it just keeps glowing. So i cannot open the cd tray to place any cd. Neither i can find it in my computer or device manager. Any help would be appreciable.