To perform a master reset on nuvi 30, 40, 50, 52, and 54 series devices:
Note: A master reset will erase all favorites1 and will restore your device to the default factory settings. If you would like to back up your favorites to your computer, you can find instructions to do so here.
The device will now reset. Follow the on-screen prompts and then place your device in an area with a clear view of the sky until it acquires satellites.
1Although the master reset will erase all saved favorites, any loaded custom points of interest will remain intact on the device.
Link referenced in this article: