Disk Management says my SD card is "Unreadable"

I need help. Disk management says my memory card is unreadable. I tried changing its letter to make it visible on my pc but i couldn't because its "unreadable". How can i deal with this? I tried searching and searching for details and nothing popped up about disk management saying "unreadable". Please Help. But whats interesting is my freakin' nokia can actually read the sd card and it can also play my music, show images(and my p*rns and stuff)but i still cant format it by my cellphone. It just loads and loads until my cellphone crashes without my sd card being formatted. HELP MEEEEEE.