If the lock switch is in the open position, it usually means the flash is in a permanent read-only state. When the lifetime of the flash is close to being used up, this is a safety feature to preserve the data as reading doesn't do much harm to the card, if any at all. They allow this as a means to move the data, at most. Be glad it acted this way, since a lot of cheap cards which do not self lock tend to fail and take out whatever is on the card. Having to buy a card on short notice is far from ideal sure but I want a chance to save what's on it.

If you want to try and see if it can be fixed, backup the card to a PC, and then format it in the camera and see. In most cases, the flash is end of life and it will fail as it's a firmware level lock.