Canon power shot SD200

You can take out the memory card from camera and then download a memory card recovery software to recover photos from memory card, you can refer to this tutorial that helped me before
http://www.asoftech.com/articles/how-to-recover-lost-photos-from-memory-card.html


If needed, you may do a quick format of the memory card and then use asoftech data recovery to recover your files.

Nowadays so many data recovery companies provides data recovery software. You should compare the rate and choose a best one according to fix memory card error

You can check the a good data recovery software at: http://www.any-data-recovery.com/product/photo-recovery.htm

Solution: Try another memory card and/or format card and try again

On Camera LCD screen displays No Memory Card, Memory Card Error, Unrecognized File Format, Incompatible JPEG, or "?" marks for images when card is inserted in the camera or while attempting to Playback images. Click here for information on Corrupt images on memory card cause a blank event window
If the camera displays Memory card error or No Memory Card when a memory card is inserted or any of the above error messages, make sure that the card is inserted properly. If this is the case, you may wish to Format the memory card in the camera using the Setup Menu option [Format] as shown below. Please be aware that formatting the memory card will remove any images currently stored on the card along with any other data. This can also be caused when images shot with another camera are stored on the memory card.
If after formatting the card in the camera the error persists, try another memory card. If this occurs with only the one card it is likely that the memory card is defective, if the error persists over more than one card the camera may require service. If the card appears to be defective you may wish to contact the memory card manufacturer.
Warning: Formatting the memory card will cause all of the images stored on the memory card to be erased. If the camera will not recognize the memory card and will not allow downloading of the images you may wish to try and retrieve the images using a commercially available memory card reader.