How do I restart my iPad mini? I can't restart my iPad mini by holding the power button and even in the powwr button in AssistiveTouch.Furthermore,I can't use any app that needed wifi.Lastly, my battery life is staying at 96% even after a couple hour.Please tell me how to fix it .tq
Try doing a "forced restart."

https://support.apple.com/en-us/HT201559

"You should force restart your iPhone, iPad, or iPod touch as a last resort, and only if it's not responding. To force restart your device, press and hold both the Sleep/Wake and Home buttons for at least ten seconds, until you see the Apple logo." 

When you see the Apple logo, release both buttons.