The SD card 512mb has been working fine about 3 years,then the camera started taking only blank photos. What can I do?

Buy another SD card and insure the memory size of the new card is compatible with the camera... some cameras are very limited in the size of cards they can read.

Are you sure it is set to save images to the card and not the camera's internal memory ?

Hi. There is a simple solution to your problem. Probably not the one you want to here, but
Your camera can only accept 512MB SD Cards. Anything beyond that Max will cause problems
for you. So the problem is the SD Card not the camera.

Could be that you have the wrong memory card.
SD600 will only work with the old SD cards, but the SD780 will take the SDHC cards.
SDHC was intended to give 4gb or more of storage, while the old SD started as 16 mb.  Different cameras have different limits, but it is always best to assume that the practical limit on an SD card is 2mb.  Even if the SD780 will take the SDHC cards, it can be more practical to only carry 2GB SD cards and know that they will fit either camera

Lets check the SD card first.

Take out the SD card and put it in external card reader connected to computer.

Copy/transfer all the photos from the SD card to computer.

goto My Computer and right-click the 'Removable Disk' (the SD card drive) and click Properties.
click Tools and click Error checking - Check now button
select the option 'automatically fix file-system errors' and click Start button.
if any errors was found and fixed, you can also Format the SD card. And your SD card should not drop photos again.

Now put SD card back in the camera.

Now take 20 test photos and check if something is missing.
if not take 20 more test photos and check if something is missing.
if all is ok then you can delete all test photos and start taking normal photos.

Don't bother with a Vivitar Card (i'm not even sure they make them). Buy an SD Card from a decent brand like SanDisk, Kingston or PNY. A 512MB card will store about 200 photos with your camera. I'd recommend a 1/2gb card. More photos and can be found for peanuts these days.

The only thing I can recommend is using the brands of memory cards that Casio recommends. They are Panasonic, San Disc, Toshiba. Make sure the card is formatted with the camera before use.

http://www.mymemory.co.uk/compatible-memory/Digital_Cameras/Kodak/Kodak+EasyShare+C330_Memory_Cards

have you try to insert it to another computer?

I experienced the same problem with a 1Gb card. The Vivicam 4000 only supports SD cards no larger than 512Mb. My solution to the problem was to simply repartition the SD card into two equal 512Mb partitions using Cute Partition Manager...http://www.cutepm.com. You should be able to do much the same thing except you will have to create 4-partitions, each no larger than 512Mb. When doing so, use the FAT 16 format option. As a word of caution, after repartitioning, do not use the fomat option on your camera, or it will restore it to a single partition 2Gb format. Also, when using whichever partitioning software you choose, be sure that you have selected your SD card, and not your C-Drive. Hope this is as successful for you as it was for me.