Your laptop should have VGA and HDMI. You don't have access to any display supporting those inputs? HDMI should be on most TVs.
If you can, try connecting to a TV via HDMI. If the display looks normal in colour, then it's a fairly safe bet you have either a loose connection to the screen, or a defective screen altogether.
If turning the brightness up doesn't work, and an external display isn't an option...... your only route left is to confirm the connections and screen are not loose/damaged. Unfortunately that means opening it up. If you're not comfortable with that, a dedicated repair shop should be your next port of call.