welcome to SevenForums
I assume the USB stick is a 3G wireless broadband modem, rather than a wireless network adapter (what you would use to connect to a nearby router)?
I've had similar experiences with two such sticks on my Windows 7 laptop. As it turned out, Windows 7 just needed to install a whole bunch of drivers the first time I plugged the stick in, and as part of that install the device does indeed become "unplugged" but only for a few moments.
All I really had to do was...nothing. Have you tried plugging the stick in and just waiting for, say, a minute? Perhaps this is all that's needed in your case.