cannot slide to unlock my iphone 4S

I just did the ios 9.1.2 update and cannot slide to unlock my iphone 4S. My on/off button does not work and I have been using the virtual assisted touch button until now, however when i try to power off the device through the assisted touch, the slide to power off won't work there either. I also plugged the phone into iTunes and tried to do a factory restore but it is saying that I need to go into my device and go into the FindMyiphone and power it off in the cloud. But I cannot get into my device so I cannot do that. I get notifications etc but cannot get in there. I cannot even take calls as the slide won't allow me to.