My Toshiba e405 has stopped reading my SD cards.

One card simply doesn't appear in file explorer.

It gives me a message that some of the cards cannot be read. It tells me that the cards need to be formatted. But when I try to format the cards the machine won't format those cards. I have been using these cards for over a year with this machine.

Has anybody else experienced this problem?

Can anybody suggest a solution?

Should I perform a hard reset? Soft resets have not fixed the problem.