In the Quick Start Manual of Garmin Nuvi 255w GPS, it stated that you can reset the unit by pressing the RESET button at its bottom. However, the RESET button is not found in my Nuvi 255w.
Additional information in the Owner's Manual stated that if RESET button is not found, slide the POWER key and hold it for more than 8 seconds will do the same, but I found out doing so will go to the touch screen calibration utility instead.
Another section in the Owner's Manual under the title "Clearing User Data" stated that holding your finger on the lower-right corner of the screen while turning on the unit and keeping the finger pressed until a message appear, that will allow you to delete all user-entered information.
I tried it and a message window pops up asking about "Do you really want to erase all user data?". There are 2 buttons to select, Yes or No. If you want to try this, make sure you've backup the data in your unit before answering to Yes.
So is the Clearing User Data be the same function as performing a hard reset to the unit? I don't have the confirmed answer yet.