Vertical lines on a TV screen can be caused by a variety of reasons such as a hardware malfunction, overuse, or even damage to the TV. Here are some possible causes and solutions to fix the issue:

Possible Causes:

• Loose cable connections: Loose cable connections, such as the HDMI or video cable, can cause vertical lines to appear on the screen. Check the connections to make sure they are securely fastened.
• Overheating: Overheating can cause vertical lines to appear on the screen. Make sure that your TV is placed in a well-ventilated area and that there is enough space around it to allow air to circulate.
• Interference: Vertical lines can sometimes appear due to interference from other electronic devices. Try unplugging other devices, such as game consoles or cable boxes, and see if the lines disappear.
• Fluctuating voltage: Very occasionally, the issue may be caused by fluctuating voltage in your AC supply. The usual culprit is a surge protector. To check this, plug the TV directly into the wall outlet.
• Physical trauma: If there has been physical trauma to your TV, such as it being knocked over or struck by something, its likely a hardware issue.

Solutions:

• Reset the TV: Sometimes, resetting your TV can resolve minor software issues that can cause vertical lines to appear. Check the TV manual for instructions on how to reset your TV to its factory settings.
• Check for interference: If the lines disappear after unplugging other devices, such as game consoles or cable boxes, then interference was the cause.
• Update the TV software: If the vertical lines persist, try updating the software on your TV. Check the TVs settings or the manufacturers website for instructions on how to update the software.
• Check HDMI cables: Unplug the video cables from your TV and all connected sources, such as your Blu-ray player or console. Then, plug them back in. If you still see the lines afterwards, try a new cable.
• Get it repaired: If none of these solutions work, it may be time to get your TV repaired.

Its important to note that if the vertical lines are uniformly distributed, its more likely to be a hardware issue, while if they are only on one side of the screen, its more likely to be a software issue.