3 Answers

Deleting won't make the pictures on a digital camera erase permanently.Those deleted pictures are still stored on the memory card of your camera, they're just invisible or inaccessible.You can recover them with photo recovery software. But once the deleted pictures were overwritten by new data,they are gone for good.
http://www.any-data-recovery.com/photo-recovery-software.htm
I used this one and it worked.Anyway,you can download it and scan your memory card for free to preview whether your files can be recovered.By the way,it will show you the file name,type,date and size of your files and thumbnails for your pictures that it found on your card.Give it a shot!

Card Data Recovery is comprehensive recovery software for any Digital Media that allows users to recover deleted and lost photos, music and video files from basic format to high-end raw image formats for most popular professional digital photo camera like Pentax, Canon, Nikon, Sony, Olympus and Minolta which includes JPG,JPEG,TIF,TIFF,PNG,BMP,GIF,CRW,CR2,NEF,SR2,SRF,ORF,MRW. It also supports video & music formats including AVI, MOV, MPG, MP4, MP3, WAV, and more

http://www.card-data-recovery.com