OS X :: Folder Full Of Media Disappeared From Desktop?

I bought my iMac a year and a half ago, but I have no idea how to deal with anything when something goes wrong (because it's so rare that something goes wrong!). Here's what happened:

I woke up, went to my computer, and noticed that a folder was missing off my Desktop. It was full of movie files and it was gone. Thinking a friend had maybe accidentally deleted it, I checked the Trash, not there. I looked through Finder, nowhere to be found. I tried searching specific file names via Spotlight, no luck. I have Apple Care and I called them and the representative took me through all the steps I went through myself to no avail. She also did a disk repair and a permissions repair, no luck.

The weird thing is that if the files were really gone, I would think I would have gotten a lot of disk space back, but I didn't. I'm still where I was the last time I checked, a few days ago.

So now that I've exhausted my own (very limited) knowledge AND Apple's, I'm coming to you. The woman from Apple said sometimes things like this happen when the hard drive is old (only got the computer in April 2008) but I would think that if the files were just spontaneously deleted, I should get a few gigs back on my drive.