Programatically install `Google Play Services` in Android device

Programatically install `Google Play Services` in Android device

In My Device( Karbon A 21 Mobile Phone) , When Google Play Services are
not installed, my location object is null and while Google Play Services
installed, it returns correct location.
I know that I can check if Google Play Services are installed
using-GooglePlayServicesUtil.isGooglePlayServicesAvailable(this). But then
Can I install Google Play Services pragmatically or should I ask user to
install it manually?
Why other App shows location even if Google Play Services are not
installed? Am I doing something wrong in my code. See code below.
locationManager = (LocationManager)
getSystemService(Context.LOCATION_SERVICE);
Criteria criteria = new Criteria();
criteria.setCostAllowed(true);
provider = locationManager.getBestProvider(criteria, true);
Location location = locationManager.getLastKnownLocation(provider);