HELP! GPS not working

Recently I bought a smartphone(Lenovo A850) and the vendor helped me to root it. The mobile came back with some problems: Without any google service. So I try to reinstall them( Root Mode). Finally I can use Google Play and Google Calenadr service, but still a problem that confuses me: GPS not working! After installing some kind of ROOTTOOL I check and see what happen. After checking hardware Info Ican see" hardware.location.gps" Does it means that the phone with GPS? But really I can not see GPS ON/OFF on my LOCATION SETUP page. My LOCATION SERVICE find no GPS SETUP. I downloaded GPS Status and said that GPS disabled. Can anyone tell me how to solve this problem and any trick to know if my mobile with GPS device or not? Thanaks.