Can't detect integrated monitor. But Works in external monitor.

My screen got black, but the machine was active, then i bring my device to service center, and they return it and says there is no problem with my device, but they didn't tell me what they do, when I try turn on my device on there, it seem there's no problem as they said, they don't give me charge for this case.

after 2-3 weeks, my screen device got black again, till i write this question. So I work with my laptop with external monitor. I bet there is something I can do, before I change my integrated monitor.