Hi nir- welcome to 4WM
The FS560 is a bit long in the tooth now, so you may not get many quick answers!
Have you installed something that has caused the GPS to stop working? Was it working OK before?
If a soft reset hasn't helped, then I think you will need to do a full factory reset (remember though that this deletes all your user data and programs). If it still doesn't work, that would suggest a hardware failure.