It always says this now, and when I do it remains the same error message.

This started occuring when I tampered with the memory card and deleted something from the memory card via the comp rather than via the cam, I've tried a new memory card and the problem still prevails. Unless the memory card had AIDs I don't think the camera would have contracted a problem, what do I do, please help me, I'm really annoyed right now because I need this camera working this weekend.