If you used it in another device, it is possible that the phone is no longer registering it. Especially if it had to be formatted in the other device.
Also, if the card came from a phone that had encoded the card, it wouldn't work in another phone.
It is best to leave a SD card in its device and connect the device to say a computer, to move data. Removing the card can lead to all kinds of problems.
Have you tried removing the card, restarting the phone, and then putting it in? Or even removing it, turn off the phone, put it back in and then restart the phone.