I have an iPhone 5s iOS 8.3. Since latest update I have no service to the phone and in error I have managed to lock the phone with siri making it impossible to open it. I have tried a number of resets with no success.

I have an iPhone 5s iOS 8.3. Since my last update I can get no service to the phone. It can receive emails and texts but cannot make or receive phone calls. In an effort to fix this problem it would appear that I have now turned on Voice Over (don't even ask). Whenever I touch the screen, wether I touch the home button 2, 3 or four times, the scree remains black. Would be grateful for any assistance in this matter