My macbook air's LCD is cracked, but the screen is still intact. what are my options for repair?

My laptop broke down as it was very old. my mother let me use her macbook air while i didnt have a laptop. Everything was working fine, the macbook airscreen was intact, then later when i returned to use it, the screen was broken. The glass is perfectly intact, not even a hairline crack. However the LCD behind the glass is shattered. The shattered area is about 1"x1" in size, but as a result about 1/3 of the screen is white with coloured lines running up and across the screen. I do not know how this damage has occured, whether something has fallen onto it, or somebody has dropped something on the screen etc? there is no damage to the back casing of the macbook screen. Please help me i do not know what to do, im pretty sure that there is no way to claim warranty or anything, and i dont know how im going to afford a new LCD. any suggestions or help will be greatly appreciated, thank you.