Assuming you are in a nice open area, the satellite database is up to date (a sync will do this) and the GPS settings have not been modified to turn it off or to a non optimal satellite mode (a reset will resolve this)
1) check if you have a GPS firmware update either by checking on the watch if setup for WiFi (under setting / system / software update) or Garmin Express.
2) check that the GPS firmware version is a number and not some garbage like 0.00 (under settings / about / scroll down until you see the firmware versions for the sensors.
3) do a full system reset. I also recommend downloading Garmin Webupdater (do a Google search for it) and install the same or newer firmware.
Just read another thread where someone suggested a forced shutdown by holding the power button for 10 to 15 seconds. The had a GPS version of 0.00 before the forced shutdown but after turning it back on it had a proper version number......... worth try. Note, after a forced shutdown it takes a few seconds to power on again. Just keep holding the power button until you get the startup triangle..
