Is this on a laptop or desktop computer? When you power up the computer, does the LED on the drive itself light up? Are you familiar with checking the BIOS of your computer? Does the drive show up in BIOS?
When you first start the computer, unless you are getting a manufacturer's "splash" logo screen, you'll first see a short display that shows the video card. You'll then see the computer go through POST (Power On Self Test). During this brief period, you can press the Delete key (sometimes one of the Function keys, depending on the computer) to get into the BIOS, where you can see what devices the computer shows are installed: hard drives, optical (CD-ROM drives); floppy drives, etc.
