Screen issue

[Ojun]

I was using my hp omen laptop and all of a sudden the sreen started flickering, not quite long horizontal lines appeared on the screen, please I need solution for this and what would be the cause 

[WAWood]

This is almost certainly an indication of failing video hardware -- either the screen or the video chip or both.

You need to connect an external monitor to the laptop.

If the visual artifacts also appear on the monitor, then it is a failing video chip and since those are soldered to the motherboard, they are not replaceable.

If the visual artifacts do NOT appear on the monitor, then it is a failing laptop screen. While those can be replaced, the cost varies enormously by individual PC model.

We are not able, or permitted, to provide any repair estimates or equipment prices.
For this information, you would need to contact an HP Repair or Service Center.

Since you live outside the U.S., here is a link to HP Service Centers, by Country/Region: https://support.hp.com/in-en/service-center

Good Luck