It's a weird thing about how google maps works - it happens to me too, but only now and then, and I don't understand it. You can fix it in settings-apps-google maps-clear cache. Then reopen maps, press the button to show your location if it's not already doing so, and you should be back to normal. It may help, but isn't always necessary, to go to your location setting s and choose high accuracy, which turns on the GPS, rather than battery saving, which just locates you via WiFi and Cell signal.