Suppose you are in a situation and needed a USB stick but you only had a phone to transfer data in WP7, in case of WP 6.5 devices you would just need to go into settings and change it to sync mode.HTC even had a popup in their Sense UI that would prompt when the device was plugged into a computer.When Windows Phone 7 was launched only way to do file transfer was to use Zune Software and then use the sync tool, but the bonds at XDA developers, a fellow named MarcHoover has created a tool to enable and disable the USB Mass Storage feature on your Windows 7 device, with an easy to use interface.
The only things you need is the Zune software, and .Net 2.0 framework.According to the developer’s website, ultimate-networx.net (translated from German), you will need to run the tool as an administrator for it to work correctly. Once it is enabled or disabled, you will need to disconnect the device and then plug it back in. Upon checking drives listed in Computer (in Windows 7), you will see a device listed with the phone model, and files can be dragged and dropped to/from the device at will. So now you have transformed your Windows phone into a USB “Stick”. So head to xda-developers website and download the app from below link