URGENT PLEASE HELP your sd card is damaged try reformatting it

from yesterday my Micromax canvas tab P290 is giving message your SD card is damaged try reformatting it when i format it in my tab but it is now not reading it .I had also try to format from my PC by cmd prompt , but it saying it is raw file which window can't read , diskpart itself is not listing my SD card

please tell me some ways to make my SDHC card usable totally free if you can please recommend me software which repair SD card upto 32 GB for free

thanks in advance