dogloverjay wrote:
At first it happens when I watch movies or video: black screen gets on suddenly but I can still hear the sound so I just quit the watching and start over and can still handle. Unfortunately Now I simply get the black screen at the very beginning so that I can't enter my password to get my Mac to work...
Sounds like you display has failed...
you can plug in an external monitor and compare your results, this would be telling.
ref: If your Mac starts up to a blank screen (black, gray, or blue) - Apple Support
In or out of warranty you can get a free over the counter 'Apple Service Diagnostics' test /assessment
Make an appointment for a "hardware issue"
Genius Bar Reservation and Apple Support Options - Apple
Outside the USA
Contact Apple for support and service - Apple Support