Question Dell Laptop screen randomly on off

[Anz Black]

Dell laptop screen randomly going off with backlight also and came back after a second or 2 but sometimes screen doesn't recover at all so I have to press power button then it will recover like it was in sleep mode
This is happening totally randomly
But I faced this problem just after servicing of my laptop done by local engineer .
Please help regarding same

 

[IInuyasha74]

Sounds like part of the display has been damaged. It's possible whoever you had work on it broke something and either didn't notice or neglected to tell you.

 

[Anz Black]

But keyboard light also turns off when display goes . I don't think it's display problem only