my HTC Desire 626 still rings and works but the screen will not come on, what do I do?

[AC Question]

I was watching youtube and locked my phone, then when I tried to unlock it again the screen was unresponsive.

 

[B. Diddy]

Welcome to Android Central! Press and hold Power for about 10-15 seconds to force a shutdown. Then wait a few seconds, and power back on again. Does it work normally now?