In order to diagnose screen lines, you should begin by re-booting your computer, updating your graphic drivers and reviewing your cable attachments. To check whether the problem is in the display or in the GPU you can also test using an external monitor. Modifying the resolution and refresh rate can be used to fix some minor glitches. When the lines do not disappear or get better, it may indicate some internal damage. When this occurs, it is advisable to have professional repair to prevent additional complications or expensive replacements. Know more about pc screen lines
You can fix the screen lines by restarting the system, update drivers, check cables and also reset the display settings. After all these option if the lines rae still there then you can ask the professional for the help.