sandisk micro sdhc READ-ONLY ERROR !

my sandisk micro sdhc memory card turned readonly while on use in my nokia c1 mobile phone, while i was copying some java games. the card turned so readonly that not even a single file on that card will get deleted. it will not even get formatted. i have tried formatting on many mobile phones, card readers, and a variety of operating systems. nothing is working. but there is no difficulty in reading from that memory card, all the songs and games previously on the card works fine, the only problem is for editing, deleting and formatting. the card contains sensitive material so i cant get it replaced from the retailer since the files on it can be easily read. wat to do? it is still under warranty,the card is only one month old