Because the images that are clear LR had made good size Previews of, they are stored in the Lightroom Catalog Previews.lrdata folder which is located in the same folder as the actual catalog file.
The ones that are blurry LR only created small previews of on import and more than likely those blurry images will eventually turn to Grey boxes. Once LR realizes the real images are no longer available.
Lesson learnt. First thing you do is create backups of important images.
The real bad part is how do explain this to the Bride and Groom. Their special day and no good images of it.
Best of luck.
Long story short, the drive I was editing from crashed and burned, and I'm left with a set of wedding photos down the drain.
What do you mean by "crashed and burned?" If the drive appears unreadable, but is otherwise OK (i.e. not physically damaged) the image files may still be recoverable:
Also if this was an external drive it has been my experience that the physical hard drive inside the external case is usually fine and it is the external enclosures electronics that fail. So you might be able to take that drive out of the enclosure and connect it to your computer with another case or a USB to SATA/IDE adapter that has its own AC power adapter.