You can use a USB cable to connect your tablet to a Windows computer and transfer music, pictures, and other files in both directions. This connection uses the MTP protocol, which is supported by most recent versions of Windows. If you are using USB tethering, you must turn that off before you can use USB to transfer files between your tablet and computer.
When you connect your tablet to the USB port on your computer, its USB storage is mounted as a drive and appears on your computer screen. You can now copy files back and forth as you would use any other external device. When you’re finished, simply disconnect the tablet by unplugging the USB cable.
How to turn on or off USB tethering on Nexus 7
To turn USB tethering on or off, go to Settings > Wireless & networks > More > Tethering & portable hotspot.
How to change Nexus 7 USB connection options
To change your tablet’s USB connection options, go to Settings > Device > Storage > Menu > USB computer connection.