What does the card error mean
Can be lots of things. Would have been handy, if you had told what card you are using. Your camera can work with CompactFlash, Microdrive and xD-Picture cards.
If you did not insert the card(s) you are using, correct, or you removed the card in a wrong way, you could have damaged the cardholder, causing an error you probably can't repair yourself. The CF and Microdrive you can remove by pressing the eject button. The xD-Picture card you can remove by pressing in the card, and release it. The card comes out.
Then you could have damaged the file system, by opening the card cover, while the card access lamp was blinking. What ever card was in, the filesystem can be damaged.
Then you can have two cards in, Both, o CF of Microdrive and a xD picture card. Some settings are required for the camera, to know hat card it should use.
If you have an Microdrive, the drive can be damaged, by a magnetic file, or the drive just stopped rotating. A micro drive is actual a miniature spinning hard drive.
First check if the memory card is inserted correct. Eventually, remove it and check all contacts, on the card and in the camera. Then try formatting the card. If you think there could be important pictures on the card, put it in a external card reader and use a recovery program, to see you can recover the pictures on your computer. Programs can be found on the net.
If you can't format the card, check if you have a Microdrive. If so, try to replace that with a CF or xD card.
I hope something is to any use for you.
Next time, please give us some more details. I know you exactly see and know what is not working, but we only can use your description. And only what you give us.