Connect an external monitor. If the problem follows to the external display it's a motherboard failure and given the age it's rarely economical to fix.
If the external is fine then it's still not a sure thing but can be the LCD or connections to to LCD from the motherboard. It still can be the motherboard but the usual is a bad connection or failed LCD. A technician will have to see the laptop to make a better diagnosis.
If it is the LCD figure 50 for the LCD (example: https://www.amazon.com/Lenovo-ESSENTIAL-59373039-Laptop-Screen/dp/B00LICJ6HM ) and here about 100 for labor.
I am having display issue on my 4 years old Lenovo G500 laptop. Please see the images here - https://ibb.co/jQpRYc and https://ibb.co/gAHoDc
This issue is happening for quite some time. I have noticed that if I turn on the charger then this issue disappears. It also seems that colors like Red, Yellow and Blue triggers this issue. My laptop does not hang during the issue.
Could somebody please tell what this issue is before I take the laptop to some repair guy? Unfortunately there is no Lenovo service center nearby and in any case, I do not trust these laptop repair guys much. I may be small issue and they may charge a lot. I just want to be sure about the issue, if possible.