LG G2 vs980 not recognized by ADB devices command (Win7 on virtualbox)

When you plug the phone in, you are given options for the "USB connection method".

You must select Internet connection or Send Images (PTP) from the list in order to use USB Debugging tools.

For selecting Internet Connection, the other options sometimes include Charge phone, Media sync, and Camera.

For selecting Send Images (PTP), the other options sometimes include Charge Phone and Media Device (MTP).

Here are may be several solutions:

1) When your device connected open Device manager(default windows tool) and found Unknown device or some not properly recognized device and try to setup driver manually.

2) Enable USB debugging option in phone settings:
go to Setting->About Phone and tap several times on Build Number,
then go back (Settings->Developer -> Options) and turn it on

3) Try to update your USB driver/adb via Android Manager launched from Eclipse.

When I upgraded my LG g2 from Android 4.4 to 5.0.2, usb debugging stopped working.

I didnt have an "Internet" option for USB connection method.

Through lots of trial, error, searching, experimenting, the I found that enabling "USB tethering" (in Settings -> Tethering & Networks -> USB Tethering) did the trick. Once I enabled USB tethering, I could download debugging programs via adb/AndroidStudio. Before USB tethering enabled, adb could not recognize my 5.0.2 device.