Just an advice in the future. When the card (or any other external device) is connected to a Linux system, it can be in two states. Mounted and unmounted. If it is connected and not mounted, it will not show up in your file manager.
This usually happens when a device has a formatting Linux does not recognize (such as some Mac-specific or windows formattings).
You can check, however, if something is connected by using the command lsblk or by using the disks utility if it is under Ubuntu