How can I retrieve pictures that were deleted from my camera card?

Yes there is. Take no more pics until you've recovered your photos, take the card out of the camera. This is to reduce the chance of you overwriting some of your "lost" photos. There are many good freeware photo recovery software options that may help you recover your photos. This article reviews and outlines several of the better ones:

Yes but you will need professional help and they don't come cheap. As long as you don't take any pictures that will replace the memory spots on the card you can retrieve them. A digital camera stores the pictures you take as separate files on a flash memory card (also known as "digital film"). There are many different types of memory cards such as SD, CF, xD Picture Card, SmartMedia, Memory Stick, the MMC Card and more. In addition, each card type has different brands like SanDisk, Kingston and more. They have different sizes, capacities and appearances, but they are just the same when acting as storage to hold pictures - they are similar to your old floppy disk or hard drive. When you delete one or more pictures from your camera, your camera locates the picture files on the memory card, then "deletes" them and marks the leftover space as usable. In most cases, for fast processing, the camera doesn't delete the picture file body but leaves them as is, which makes it possible for us to retrieve them after deletion.

Just type in recover photos from a deleted memory card in the google browser and many different people have sites that sell this software for a fee. I personally used one for my computer and it retieved all lost pictures, I was amazed and most happy. Good Luck.

if you already deleted it, there's no way to retrieve it..

This link should help you retrieve your deleted pictures:

http://www.cardrecovery.com/how_to_recover_deleted_digital_pictures.asp

I've posted this answer many times.
As long as you do not use the card again you can recover the pictures.
There is free software on the internet for doing this. SanDisk provide recovery software with one of their SDHD cards that works well.

yes, you can recover deleted photos from Sony Cybershot digital camera with photo recovery software, recommended asoftech photo recovery which helped me before. you may refer to this step by step guide
how to recover photos from digital camera
the guide is easy to follow and works well for me. hope that it can help you too!

Sometimes there are other folders and the pictures can be hidden.
Also make sure to check internal memory with the card removed. Remove the memory card, turn on the camera and check if any of the pictures are on the internal memory.

Also, use a card reader for the computer instead of using the camera connected to the computer.
With a card reader you may be able to see the folders (if any) and retrieve your pictures.
Never delete any pictures or edit them from the computer to the camera. This can cause corruption and loss of pictures and files.

Always download (copy) them from the camera on to the computer.

Don't worry! 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.
Here I recommend you these software that helped me out:
Windows Picture Recovery Software