This one other way to enable your Lumia to act as a mass storage device just like plugging in a USB stick. But make sure you have Zune installed and one Lumia device connected.
What Should do :
Download the USB Enabler tool
Run the NokiaRevo_Wp7UsbStorageEnabler.exe
Click the option “Enable” then hit Quit.
Make sure to close Zune to enter the USB Storage mode
Connect your Lumia and see for yourself.
Now you can use your phone like a normal USB mass storage.
Note : This tool requires .NET 2.0.
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