Why is my screen black with some rainbow lines?

Recently I noticed my laptop screen turned black and the right side of the screen has a couple vertical rows of rainbow lines. I currently have it connected to an external display and it works perfectly fine, just the laptop screen is black and unusable. Since I know that it connects to an external display, I researched it may have something to do with an inverter because my screen brightness adjustment buttons are inoperable, or maybe it could be a faulty cable according to some sources. How would I go about fixing this problem and what could be a possible diagnosis for this? Should I go to repair shop? Or just repair it myself if it is relatively straight forward? Thank you in advance for helping me with this issue.