By pushing that button what you did was , you did a factory reset on the camera, so, now you need to set that camera up as new after that you can deal with the SD card.
I never turn the cameras off when putting in an SD card, make sure you are putting the card in the correct way and make sure to punch it down in there completely, go to advanced settings and see if your card shows up, if it does not, leave the card in and power cycle the camera and check again.
Also check this thread to see if you have a defective camera