Files in Memry card converted to unreadable files with size in GBz

i have a camera named "Canon PC 1264",,the pictures in the memory card are converted to some unknown file type with size GBz....some of the picture's folders are in the original conditions but 3 to 4 folder are change due to some known reason,, Please suggest me someone a solution,,the pics are very important.. i have attached the screen-shot image of the folder