USB_ModeSwitch

I would like to learn if it is possible to switch a modem back to its default mode with out unplugging it.
i.e 12d1 1f19 is switched to 12d1 1578.how to switch 1578 back to 1f19 or may be to 1001 identity without unplugging it.

The only way of returning to default mode is to remove the power from the modem.
You can do that by unplugging the modem or by switching off usb power if your usb host controller has an option for that.

thank you.