From last two years I am using blackberry without any problem. But yesterday suddenly it stopped getting detected as a usb mass storage device. I updated device softwares, changed the settings in memory option, enabled mass storage mode in blackberry option, but no result.
While searching the net for the similar problem, I got calfix. Just download the calfix.exe on your windows machine, if your BlackBerry smartphone is password protected, you will be prompted for the password to authorize the installation.
It will reboot you device and voila again you can use your blackberry as a mass storage device.