Internet connection

Just a moment ago, my dad called me up asking me about his internet connection. He said that last night he had gone to youtube then suddenly the computer screen black out. What's wrong? I don't know as I am not at his place. My sister was there and she doesn't know anything about computer and internet. She just know about using internet to do her work.

My sister wasn't happy at all and she is now on the way back. She didn't get to do her work at all.

My dad has called the technician nearby to check on his computer but the guy wasn't around at the moment. Hopefully he's able to get his computer working again. My guess is the monitor screen! Hmm... how to say... monitor screen no more heart beat? lol