Can I update Garmin GPS for mountaineering? Help me!

I am a mountaineer and always planning for mountaineering trip at Rocky Mountains, or hilly regions. I am using Garmin GPS device for driving the car safely. My Garmin device shows me all the directions of routes, paths or traveling ways, so I can reach at the right place without facing any kind of troubles. From last week, My Garmin GPS device is showing me the wrong directions, but I don’t know actual reason, so I am into a big trouble. I am looking for Garmin GPS update. So please anyone suggest me easy ways for Garmin GPS update.