black screen on startup windows 10

hi when i turn my computer on it loads up but then a blue box appears and then dissappearsand it stays on a black screen but i can still hear sounds through my headphones that i am using can someone help me please as to why this is happening also i turned it on yesterday did exactly the same but this a blue light appeared in the left corner of the screen and then stayed black again sounds were still coming out of headphones. can anyone please help me with why this is happening thanks

https://m.youtube.com/watch?v=Gc_3cxS2jdU

https://m.youtube.com/watch?v=9fapxkLcOiU

here are both video links via YouTube showing what is happening

Start the computer, wait ten or fifteen seconds, then press and hold the power button until the computer shuts down. Do this twice and the third time the computer should boot into the recovery environment.

Ben

okay will wait till brother gets here to help this week then i will try your way okay

brother says that is going to do nothing will wait until he comes round okay

found problem cable connecting screen to computer is knackered works with hdmi cable