This will give you a clear picture ,@Anders_ASUS
When i press smart key ones the app gets selected in app drawer and when i double click it the app opens.
In the home screen the first app (ZenTalk webpage) turns on.
Revanthmines too solved after a os reset like i mentioned before.. thanks guys
@hegemony3 hey i went for service center and they did an OS reset and from then it's working fine for me and even my battery life improved after that . So i recommend you to go service center . And it's free of cost because our phone is under warranty . It's not been an year also for 6z release . Better to take to service center . For me it got solved after software reset .