Yeah! I also agree to use a SD card data recovery program in your case.

In fact, there are plenty of data recovery program available online that can help restore your deleted photos back. Some of them are paid and some of them are free. But, not all of them can work as efficiently as you think.

So, if you are really suspicious, you can firstly take chances with some data recovery freeware:

http://www.piriform.com/recuva

http://www.cgsecurity.org/wiki/TestDisk

http://blog4mark.blogspot.com/2012/12/sd-card-photo-recovery.html

I hope one of them can help you out at least.

PS: Before the data recovery process, you’d better never save anything new on SD card in case of any data loss. After the data recovery process, you’d better not save the restored data on the same card in case of data recovery failure. After experiencing this trouble, I hope you can learn a valuable lesson to back up everything important well in the future.

Thank you for your recommended data recovery freeware, Alvis0039!
I really know nothing about undeleting a SD card. But, after reading your description, I have learned a lot. By using your mentioned data recovery freeware, I finally re-access all my needed data on it. It is really great! Thank you very much!!!