Memory Card Has RAW Format

"My memory card has changed to RAW file system which was FAT32 before. I have used this memory card for a few years in my mobile phone. Yesterday, I plugged my mobile phone to my computer through a USB cable and saved some music to the memory card. When I was transferring the music, Windows system says please insert a disk into drive. Then, I unplugged the mobile phone and reconnected it to my computer again, this time the Windows recognized my memory card as a RAW drive and it prevents me from accessing any data on the card. I also tried to move the memory card out of my mobile phone and connect it to my PC via a card reader, but system still detected it as a RAW drive. Can anybody tell me what is wrong with my memory card and how to convert RAW to FAT32 with data back?"

Memory Card Not Formatted Nokia

"I cannot access the memory card which has used for my Nokia mobile phone for about two years. The card still worked normally yesterday, but today it says that the memory card needs to be formatted. All files stored on this memory card become inaccessible. Nokia mobile phone always reports the same error message that memory card needs to be formatted. Connecting the card to another mobile phone, I still get the same error message. Then, I inserted the card to my laptop, and Windows system still said that memory card is not formatted. How can I fix thenot formatted error on Nokia memory card? Is it possible to get back those inaccessible files?"