It sounds like the memory card is not stored on your device properly (I don't know if you're talking about a phone or a camera etc). To see if this is the case, take the memory card out and see if the pictures are there. If so try different ways of putting the memory card in.
this happened to me too, i had a 6 gb memory card, and on my camera it would only let me take 3 pictures, so i just got a different memory card and it worked fine. you may need to try formatting your memory card or resetting the camera
Is it a memory card in your phone? If so make sure that you are saving things to the memory card and not the phone. I had that trouble before and realised I was saving them to the wrong place.
Not sure if I made that clear enough sorry, take the memory card out and see if the picture are stored on the device still as opposed to them being saved on the memory card.
yeah, it is it's on a camara
no on a camara