Cannot copy X file. The Disk is write-protected. Remove the write-protection or use another disk?

does anyone know how to remove the write protection on my MMC card? hey, it has no lock.. i can't find any slider on its sides. does anyone here knows how to solve this using my computer? i tried formatting it but it can't be coz it's write protected. is there any program that i can download that will remove its write protection?