The memory card may have a lock switch depending on the card type. If the memory card is locked, release it before inserting the card into the machine.
Depending how you insert an SD memory card, the write protect lock may switch to the lock position and you will not be able to write from a computer. If this occurs, release the SD memory card lock switch. Be careful not to engage the write protect lock, then insert the memory card.
Please refer to the memory card's instruction manual or contact the manufacturer for instruction on releasing the lock switch.