Hi, and thank you for asking your question.
If you are having this issue with a laptop, please do this now:
Press and HOLD down the Power button for atleast 30 seconds (even after the screen has switched off), and then release the button.
Next, press the Power button one more time to turn it back on - it should boot up all right now.
If you need any further assistance with this issue, please be sure to reply back to me below.
Otherwise, if you could kindly click on (and submit) one of the star buttons at the top of this page to rate my service, I'd greatly appreciate it. Thank you.