firstly, iso was stat resetting to 100. I put iso 1600 and when i took a photo, it was dark and iso was 100. this problem has been repeated. Then I have changed a memory card and a problem with iso was gone. But when I took a photo, on display wasn't the photo I took, but a fifth behind the new photo. After that, I've got an error "This memory card cannot be used. Card may be damaged. Insert another card". Then I have formated a (second) memory card, put another (third) memory card and after few shoots i've got message "File contains no Image data" and the photos i took were gone.
Is this a memory card problem or it is something with electronics on my camera? The part with iso is confusing me and that's why I think that this is not a problem with a memory card.