How did an entire folder of image files just disappear from my computer?

I spent almost 5 hours last night editing images. All of the originals and edited images were saved together in one file on my desktop. A moment ago, I booted up my computer and opened the file (with plans to burn a disc for backup). NOTHING THERE! What in the world could have happened? Luckily, I tossed the ones I needed into a zip-file last night and uploaded everything to my lab. Unfortunately, if I need to make changes or place another order from one of the originals…I can’t. Everything’s gone. How does an entire folder of image files just disappear? We’re talking about at folder that was at least 125MB. I checked the recycle bin…nothing there either. What’s up? Can I recover them somehow?