After troubleshooting  The solution was to close the laptop by pressing the power button for 15 sec then open it :') And bingo it works 
I have  windows 10 in my laptop  The bios has a new update and I update it  After finishing it start to restart But it has been more than 3 hours restarting and the screen is black while the lab is working :") is that normal ?    Ps: I don't know which board is my lab but it is a gaming lab
Dell g3 3500 bios update