Touchscreen not responding.
There are three levels of fixes, please try them in order:
1. Reset the GPS using the Reset button, on the back, just under the Antenna Hinge. Resetting will turn off the GPS, and then turn it back on, if connected to power. Test, if fixed, great, otherwise, go to fix 2.
2. Turn the power off, then press and hold the powerbutton for up to 2 minutes. The GPS will turn on, and display a "PreBoot Mode" message. When that message disappears, and the screen calibration screen appears, follow the on-screen instructions, and you are fixed. If you still cannot use the touch screen, repeat fixes 1 and 2 several times, just to be sure., then go to fix 3
3. The touch-screen glass has probably broken or lost its connection with the GPX motherboard. You can order new touch screen glass on the web and install yourself, if you are techy in nature, otherwise do a search for "garmin nuvi 660 repair" and choose your service.