How do you reset garmin nuvi 760?

To reset the unit if it is hung, slide the power switch and hold for 8 or more seconds until the unit resets.

To reset back to factory settings and erase all user data, press and hold the lower right corner of the screen and then power the unit on, a dialog will come up asking if you want to "Erase all user data", select yes. This option only erases data in the unit's memory that isn't accessible to the user (ie. what isn't accessible when you connect the unit to your computer). It doesn't erase any .gpi or .gpx files you loaded (if your .gpx files contain any waypoints then they will automatically be imported into your Favorites), it won't erase any mp3's, jpg's or any other files that you have loaded.