Try reboot device.
Start device with start button on side of phone.
Screen will go to light black color.
Long press Start button for menu:
Reboot item is in same level like Start button.
Click on the screen – (Hear a click)
Now find OK button , it is under Reboot item on right side of screen.
Press OK (Hear a click)
Wait a moment.
If device to do nothing , try short press Start button (sreen will black)
and again to press Start button. If screen go to light black color,
try again find Reboot item as written above.