My camera has been working fine. I keep it in it's protective carrying case - nothing damaging has ever happened to this camera. 

I took it out a few days ago and the display showed that my file contained no data. Thinking this was strange, I took several pictures: it was VERY slow at letting me review my pictures but eventually I was able to see the few I had taken. 

Several minutes later there were no pictures again and then the screen read that the 'memory card cannot be used and may be damaged'. I changed out cards and the same thing happens. 

Sometimes the shutter would not even release when I take a picture, other times it will but shows a quick black image but then won't let me review it in playback mode. 

I can't even get to playback mode! What is going on?