Seeing black horizontal lines on your phone screen can be worrying, especially if your phone was working fine just a few minutes ago. Your first thought is usually the worst-case scenario — broken screen, expensive repair, or a trip to the service centre.
But that’s not always how it plays out.
In a lot of cases, the problem turns out to be something small and fixable. And even when it isn’t, a few quick checks can help you understand what’s going on before you spend money on repairs.
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What Causes Black Horizontal Lines on a Smartphone Screen?
Black horizontal lines don’t appear for no reason. They usually show up when something goes wrong between the phone’s software and the display — or when the screen itself has taken a hit.
Sometimes it’s just a software glitch, especially after an update or a long stretch without restarting the phone. On the other hand, it could be physical, like a drop, pressure on the screen, or even moisture sneaking inside. In more serious cases, the display panel itself starts to fail.
The trick is figuring out which category your phone falls into.
- Software glitches or display driver issues
- Loose or damaged display connectors, often after a drop
- Physical screen damage, including cracks or pressure marks
- Internal hardware failure, such as LCD or OLED panel issues
- Water or moisture exposure affecting internal components
Knowing the cause helps you decide whether the issue is fixable or needs professional repair.
How to Fix Black Horizontal Lines on Your Smartphone Screen
Restart Your Phone
This sounds obvious, but it’s worth doing before anything else.
If your phone has been running for days or just installed an update, a simple restart can fix odd display behaviour. Close whatever you’re doing, restart the phone normally, and give it a minute once it’s back on.
If the lines disappear, you’re done. It was likely a temporary software issue.
Update the Phone’s Software
If restarting doesn’t help you, then the next thing to look at is phone’s software.
Display bugs can creep in when a phone is running outdated software or when an update didn’t install properly. Head into your phone’s update section and see if there’s anything waiting. If there is, install it and check the screen again afterward.
Check for updates:
- Android: Settings → System → Software update
- iPhone: Settings → General → Software Update
It’s a small step, but it fixes more display issues than most people expect. Installing the latest update often resolves display-related bugs and driver issues.
Clean and Inspect the Screen
Before assuming something serious, take a moment to clean the screen.
Turn the phone off and wipe the display gently with a microfiber cloth. Once it’s clean, look at it under good lighting. Sometimes smudges or residue make lines look worse than they are.
If you notice cracks, pressure marks, or uneven areas after cleaning, that’s usually a sign the problem is physical — and software fixes won’t help much.
Check for Loose Hardware Connections
This step tells you a lot without opening the phone. You need to hold the phone normally and slowly tilt it or move it slightly while watching the screen. If the black lines flicker, shift, or change, it often points to a loose internal connection — something that can happen after a drop.
Important: At this stage, it’s best not to try fixing it yourself. Modern phones are packed with fragile parts, and opening them without experience often makes things worse.
Factory Reset (Last Resort)
A factory reset isn’t something you jump into, but it can be useful as a final check.
If there’s no visible screen damage and nothing else has worked, resetting the phone can confirm whether the problem is software-related. Just make sure your data is backed up first, since everything gets wiped.
Then:
- Android: Settings → System → Reset
- iPhone: Settings → General → Reset → Erase All Content and Settings
If the lines are still there after a reset, you can safely assume it’s a hardware issue.
When to Seek Professional Repair
If the lines stick around after all this — or if you notice cracks, liquid damage, colour issues, or touch problems — it’s time to see a technician.
A repair professional can tell whether the screen, internal connectors, or the phone’s main board needs attention, and whether repair is worth it.
Preventing Horizontal Lines in the Future
You can’t prevent every screen problem, but a few habits help.
Using a good case, adding a screen protector, avoiding pressure on the display, and keeping the phone away from water and extreme heat all reduce the chances of display trouble later.
Bottom Line
Black horizontal lines on a phone screen look serious, but they don’t always mean the phone is done for. Start with the basics, move step by step, and pay attention to how the screen behaves. Even if the issue turns out to be hardware-related, going through these checks helps you understand the problem before heading to the service centre — and that alone can save you time, stress, and sometimes money.
