SD card rendered to read only

Micro SD ultra 16gb ,
product code - SDSQUNB-016-GN3NM

I am using this card since oct15 it was working well and gud but now from last 15 days m unable to delete/copy/move anything to it neither its permitting to format but its working
What to do now plzzz help

I would say put in a claim (RA) with SanDisk for a replacement under warranty.