Diagnosis
A consistent vertical line of pixels that are always off (black) or always on (stuck color) indicates a physical failure of the LCD panel's internal connections. This is a hardware defect.
How to Fix It
1. Power cycle the monitor completely (unplug for 60 seconds). This rarely fixes a permanent line but rules out a temporary glitch.
2. Gently but firmly massage the area of the line with a soft, microfiber-clad fingertip. Do not apply excessive pressure.
3. Run a pixel-exercising video (flashing colors) from YouTube for several hours. This can sometimes revive stuck pixels but rarely dead ones.
4. Check HP's warranty status for your monitor. Panel defects are typically covered under the standard limited warranty (often 1 year).
If That Didn't Work
The panel is faulty. There is no software setting, driver update, or cable change that will repair a physical line of dead pixels. The only resolution is a panel replacement, which is not cost-effective outside of warranty.
Heads Up
HP's pixel policy typically requires a certain number of defective pixels for a warranty claim. A single vertical or horizontal line often qualifies as a 'line defect', which is usually covered. Have your serial number and purchase proof ready when contacting support.