Help Needed (Windows 7) Laptop has suddenly got a black horizontal line

Is this line near the bottom of your laptop's monitor?

Try and describe the situation a little more.

Try to enter bios and see if it's there as well.
If not - this is software issue. If yes - it's either screen broken or connector.

Sounds like ardware issue. Is it getting bigger?

Also try, if you have some, to plug the laptop to an external monitor. If it reproduces the same line -> software. If not -> hardware.

A friend of mine had a little vertical line once, near the top right of the screen. Turned out to be a physical internal screen break; applying gentle ppressure with a single finger on the area would permanently make it bigger (I would suggest against trying it, at least if you want to salvage it for whatever time it may hold on; though with just closing and opening the screen might slowly but consistently worsen the issue if it is the case).

But what 76561198082881386 suggested, using BIOS to see if it appears also there, is the better method. No software involved.

I had a similar issue. It was dead pixels. Single pixel height horizontal line, kept getting longer, then more pixels around it going black. I pressed on the screen and got it to move around a little, and the black turned blue, but never got it to look perfect. You should be able to replace the screen, but whether or not that's cost effective is another matter.

i made a steam group for windows 7 steam users. you could hit them up.
https://steamcommunity.com/groups/Windows7ForeverUpdateNever

Most likely your display is faulty and needs to be replaced. With lesser probability it could be an issue with your GPU which is difficult to fix DIY as this shit is soldered to the mainboard normally.

It should be the screen

This kind of line artifacts usually indicate a hardware issue. Either a problem with the screen cable inside the laptop or the screen itself is starting to die..