Card Won't connect to camera and I'm loosing it

[xifa4]

Ok, I bought a used camera semi-recently for a good price. Everything works well so far except the fact I can't connect the camera to the card.. It keeps saying I need to either change the card (Have done this multiple times) or format it (Will not allow me to do so on the camera itself)

So.. What the hell do I do? The camera was a lot cheaper then a new one, but it still was a good chunk of money! Is there a way to reset the camera entirely? Do I need a very specific card? I'm so confused.. I just want to take photos!

[rs-eos]

What camera model? What specific SD card (brand, capacity, full-sized vs micro) do you have?

[normadel]

Where'd you get the camera? A private party? A used equipment dealer? 

Buying a particular camera because it is cheap is not a good plan unless it comes with a warranty and is easily returnable. 

That being said, what camera is it and what type of memory card does it use? If it's a CF card, look down into its slot and see there are any bent or missing pins. If SD card, look into the slot to see if any contacts are bent/mangled or missing.