Answer to: Why is my SD card not working with my HTC Desire?The SD card might not be in the phone, take the back of the phone off to see if the SD card is there. If the SD card is in the phone, check that it is inserted properly. If the SD card is put in the slot in the wrong direction it will not function. If the SD card is not missing and it is installed correctly, it may be that the memory is full. Try deleting some items from the memory card, if that allows you to save more stuff then the card has probably reached its maximum memory capacity. If this is the case, replace the SD card or delete more of the items on it.