SD Card becomes read-only, hence camera, WhatsApp media cannot be downloaded

A

AC Question

When i put in an SD Card it was fine and worked OK for an year.
My Micromax Android One came with KitKat.
I upgraded to Lollipop and later Marshmallow and it worked fine.
However, since 15 days the SD Card must have become read-only.
I discovered this when my Camera could not save images.
I gave a feedback.
Later FM Radio recording could not be saved.
I tried removing the card, replaced it with a lower capacity card (4GB instead of 8GB).
Kindly help me in solving this problem.