Does anyone know how to retrieve pictures from a digital camera when the memory card is corrupted?

The files were readable before and for some reason now they are not viewable. They are still there, but cannot be copied or accessed by the computer (via the USB port) or on the camera itself. the camera is a nikon coolpix 5600.
they show up as a file called g
and also other files with file extensions .rar
I was told by a camera shop that they could be retreived but at a steep price. Some of the pictures are viewable but about 2/3 rds arent but are still taking up memory on the sandisk 1 Gig card.
I cant even drag and drop the files to a hard drive to copy the files to create a back up in case this file retrieval thingy fails. does anyone know what to do or have gone through the same thing? also could airport security scanners have caused this?
thank to all who respond!

You can try to retrieve the photos with Photo Rescue - it's a utility that's recommended in some digital photo forums. You can download a trial version here:
http://www.datarescue.com/photorescue/

you cant, it is impossible

If your card is a Lexar, contact the company. I've heard of people sending in their corrupted cards, and getting back new ones WITH all their pictures intact. The other major companies may have this kind of service available. Call them.
Of course, if your pictures are really special and valuable, you may want to just spend that money.

Hi, I recommand you to try google picasa.

picasa is a Google's photo software. It's what should've come with your camera.

It can Edit , organise and Share you picture and small video flips.

It's very easy to use and is free, just like Google

Download it free in here:

http://www.bernanke.cn/google-picasa/

Good Luck!