hmm what happens when u erase/quick format ur card, is that the header files that link to ur actual pixel data is deleted, that means ur actualy pixel data is still intact on ur memory card (unless it's been overwritten by some other data that you saved, and if u didn't do a full format).
I heard of some shops that can recover this data for you, but think they're quite pricey. btw I don't know any of this shops personally, but just to let you know of this option.
What you see in LR is just the jpg thumbnails. When LR imports your files from your media, the default settings is to copy the files to your HDD. So you should have a copy of the photos in your HDD and in your SD card.
First thing to check is did you copy the files into an external HDD and you forgot to turn it on?
Move your cursor to the folder in LR and it should tell you the path to the photos. Did you move the folders to somewhere else? If so, you can just link the folders in LR back to the new folder locations. Do a search in windows looking for *.CR2 for e.g
hmm... if lightroom copied the images, it would have taken the reference from the new location rather than showing the 'missing' notification, no?
>TS - you mean u actually loaded the contents of your SD card DIRECTLY into lightroom without copying them first into the computer?
chances are that the changes you did to the images in lightroom would have been lost even if you can recover the images using software.
best solution for you is to try to recover the images using recovery software, copy them into the comp, then load them into lightroom again from your comp and not the SD card.