Ouch.

Sounds like a system problem, not a LW one.

What version of OS X are you using?

You could try the easy fix for most OS X versions--shut down the computer for a couple of minutes, then do a Safe Boot (hold down the shift key right after the startup tone). With luck, that will fix the problem.

To trouble-shoot hardware problems like the drive not showing up, search the http://discussions.info.apple.com/ for similar problems.