My devour locked the sd card after I moved some files from my PC to my phone. I spent a few hours till my phone gave me a clue. so I tried this and it worked.
I plugged my phone into my computer. Chose manage memory card option. Transfered data fine. Then using notifications menu on phone, Chose usb connections, switched to modem mode. Stopped usb device with windows, and unplugged. Memory card unlocked now.