I don't think I can help you, but those who can would need some further information: First, which Mint version are you using, on what hardware? You mention first memory card, and then memory stick. Is this a USB stick, an SD card, or what? How is it connected, via a built-in card reader, USB adapter, or USB socket on the motherboard? Do you have alternative sockets you could try?
If you give some more to go on, maybe somebody can help.
Can not read the resource is like i-saw-it-arrive-but-i-did-not-see-it-leave. Pretend it's still there and use safely-remove-device, then remove the device. Not every connection survives repeated use so it might just be a bit of grubby on the card connector or a bit of wobbly on the USB.
Still not work? Do you behind a proxy? Let's Ping!