If you can’t find the “Settings” app, swipe down on your home screen and enter “Settings” in the Spotlight search bar.
If this slider is disabled, Location Services may be disabled in the “Restrictions” menu. See the next section for details.
Select Never to disable Location Services completely for the app. Select While Using to limit Location Services to just when the app is open and active. Select Always to allow Location Services at all times. This is only available for select background apps, such as Weather.
If you can’t remember your Restrictions passcode, try 1111 or 0000. If you have completely forgotten your Restrictions passcode, you’ll need to restore your iOS device through iTunes to reset it. See Restore an iPhone for details. Make sure to backup any important data before restoring.