From those very nice people at Lightstalking comes this tutorial on recovering lost images. Having had this happen to me 4 times I know this is a very stressful experience so any help with recovery is worth reading about
One of the very worst things a photographer can suffer is the loss of images from a memory card. It is a feeling that kicks you in the stomach, even if they just some quick family shots, for professionals it can literally be a disaster.
There can be a number of reasons that images are lost from memory cards, faulty cameras are amongst the rarest of these. The most common causes are faulty memory cards and operator error.
Faulty memory cards are most often associated with buying cheap unbranded cards or either knowingly or unwittingly buying fake cards. Operator errors tend to stem from accidentally formatting the card, deleting all instead of one image and removing the card whilst the images are still being written. READ MORE HERE