I have a Samsung Grand 2, OS v Android 4.4.2. On 24th Oct 2014 a new OS update was installed post which lot of Apps stopped working. I connected the phone to laptop and tried deleting few files from phone memmory but getting error message drive is locked. Now i am unable to read or delete any files on phone memmory but SD card is working fine. Can someone help me how to resolve this issue? Only chnage i can see with the update installed was knox application was installed in my phone. I am not able to uninstall the application. My phone is not rooted.